Attackers in California shooting had thousands of bullets

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San Bernardino Killers Purchased the Weapon Legally

SAN BERNARDINO, Calif. (AP) — San Bernardino gunman Syed Rizwan Farook had been in contact with known Islamic extremists on social media, a U.S. intelligence official said Thursday, and police said he and his wife had enough bullets and bombs to slaughter hundreds when they launched their deadly attack on a holiday party.

The details emerged as investigators tried to determine whether the rampage that left 14 people dead was terrorism, a workplace grudge or some combination.

READ MORE: The last time a shooting involved multiple gunmen was Columbine

The husband-and-wife killers were not under FBI scrutiny before the massacre, said a second U.S. official, who likewise was not authorized to discuss the investigation and spoke on condition of anonymity.

See photos from the scene:

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Attackers in California shooting had thousands of bullets
This July 27, 2014 photo provided by U.S. Customs and Border Protection shows Tashfeen Malik, left, and Syed Farook, as they passed through O'Hare International Airport in Chicago. The husband and wife died on Dec. 2, 2015, in a gun battle with authorities several hours after their assault on a gathering of Farook's colleagues in San Bernardino, Calif. (U.S. Customs and Border Protection via AP)
This undated combination of photos provided by the FBI, left, and the California Department of Motor Vehicles shows Tashfeen Malik, left, and Syed Farook. The husband and wife died in a fierce gunbattle with authorities several hours after their commando-style assault on a gathering of Farook's colleagues from San Bernardino, Calif., County's health department Wednesday, Dec. 2, 2015. (FBI, left, and California Department of Motor Vehicles via AP)
An investigator looks at a Black SUV that was involved in a police shootout with suspects, Thursday, Dec. 3, 2015, in San Bernardino, Calif. A heavily armed man and woman opened fire Wednesday on a holiday banquet, killing multiple people and seriously wounding others in a precision assault, authorities said. Hours later, they died in a shootout with police. (AP Photo/Jae C. Hong)
FBI agents search outside a home in connection to the shootings in San Bernardino, Thursday, Dec. 3, 2015, in Redlands, Calif.. A heavily armed man and woman opened fire Wednesday on a holiday banquet, killing multiple people and seriously wounding others in a precision assault, authorities said. Hours later, they died in a shootout with police. (AP Photo/Ringo H.W. Chiu)
Investigators search for bullet casings at the scene where Wednesday's police shootout with suspects took place, Thursday, Dec. 3, 2015, in San Bernardino, Calif. A heavily armed man and woman dressed for battle opened fire on a holiday banquet for his co-workers Wednesday, killing multiple people and seriously wounding others in a precision assault, authorities said. Hours later, they died in a shootout with police.(AP Photo/Jae C. Hong)
Investigators gather around a Black SUV that was involved in Wednesday's police shootout with suspects, Thursday, Dec. 3, 2015, in San Bernardino, Calif. A heavily armed man and woman dressed for battle opened fire on a holiday banquet for his co-workers Wednesday, killing multiple people and seriously wounding others in a precision assault, authorities said. Hours later, they died in a shootout with police. (AP Photo/Jae C. Hong)
REDLANDS, CA - DECEMBER 2: A SWAT team member stands watch with a rifle pointed at a home being investigated by police is shown after a mass shooting at the Inland Regional Center in San Bernardino December 2, 2105 in Redlands, California. Multiple fatalities and injuries were reported in the shooting (Photo by Marcus Yam/Los Angeles Times via Getty Images)
Law enforcement officers investigate a suspicious bag, later found not to be a threat, on Victoria Avenue after a mass shooting at the Inland Regional Center on Wednesday, December 2, 2015 in San Bernardino, California. At least 14 people were killed in a gun attack on a holiday party, triggering a massive manhunt that ended when police shot dead two heavily armed suspects -- a man and a woman -- on a quiet residential street. AFP PHOTO / PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
SAN BERNARDINO, USA - DECEMBER 02: Yellow stripe is seen as the US Security Forces secure the area following a shooting that killed multiple people at a social services center for the disabled in San Bernardino, California of United States on December 02, 2015. Two suspects in a deadly mass shooting that killed 14 victims at a social services facility in California were killed after a confrontation with police, authorities said Wednesday. The initial shooting occurred earlier Wednesday when at least one shooter opened fire in San Bernardino at the Inland Regional Center, which provides services to persons with developmental disabilities and their families. At least 17 others were injured. (Photo by Mintaha Neslihan Eroglu/Anadolu Agency/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: A police officer officer guards a police line as officers prepare to raid the home of one or more suspects of a mass shooting at the Inland Regional Center by multiple gunmen on December 2, 2015 near San Bernardino, California. Police continue to investigate the shooting that left at least 14 people dead and another 17 injured. (Photo by David McNew/Getty Images)
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Authorities surround the scene following a shootout Wednesday, Dec. 2, 2015, in San Bernardino, Calif. Multiple attackers opened fire on a banquet at a social services center for the disabled in San Bernardino on Wednesday, killing multiple people and sending police on a manhunt for suspects. (AP Photo/Jae C. Hong)
Authorities guard the perimeter near the location of an officer-involved shooting Wednesday, Dec. 2, 2015, in San Bernardino, Calif., following a shooting that killed multiple people at a social services center for the disabled. (AP Photo/Damian Dovarganes)
SAN BERNARDINO, CA - DECEMBER 2: Police place a marker along E. San Bernardino Ave. where a shootout occurred December 2, 2015 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for suspects still at large. (Photo by Rick Loomis/Los Angeles Times via Getty Images)
Armed police personnel walk along closed off streets in the San Bernardino neighborhood near the intersection of Richardson and Gould where a house was searched on December 2, 2015. A man and a woman suspected of carrying out a deadly shooting at a center for the disabled in California were killed in a shootout with police, while a third person was detained, police said. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: A police helicopter circles as officers search for a possible suspect following a shootout with suspects of a mass shooting at the Inland Regional Center by multiple gunmen on December 2, 2015 in San Bernardino, California. Police continue to investigate the shooting that left at least 14 people dead and another 17 injured. (Photo by David McNew/Getty Images)
Law enforcement officers search for the suspects of a mass shooting December 2, 2015 in San Bernardino, California. A man and a woman suspected of carrying out a deadly shooting at a center for the disabled were killed in a shootout with police, while a third person was detained, police said. AFP PHOTO / PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
A police officer deploys tape to an area near where authorities stopped a vehicle in San Bernardino, Calif., Wednesday, Dec. 2, 2015. Multiple attackers opened fire on a banquet at a social services center for the disabled in San Bernardino on Wednesday, killing multiple people and sending police on a manhunt for suspects. (AP Photo/Damian Dovarganes)
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Law enforcement officers search for the suspects of a mass shooting December 2, 2015 in San Bernardino, California. A man and a woman suspected of carrying out a deadly shooting at a center for the disabled were killed in a shootout with police, while a third person was detained, police said. AFP PHOTO / PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: A SWAT unit mobilizes near Richardson Street after a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Marcus Yam/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Law enforcement officers search for a possible suspect following a shootout with suspects of a mass shooting at the Inland Regional Center by multiple gunmen on December 2, 2015 in San Bernardino, California. Numerous deaths and injuries have been reported. (Photo by David McNew/Getty Images)
Law enforcement officers search for the suspects of a mass shooting December 2, 2015 in San Bernardino, California. A man and a woman suspected of carrying out a deadly shooting at a center for the disabled were killed in a shootout with police, while a third person was detained, police said. AFP PHOTO / PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
In this image taken from video, armored vehicles surround an SUV following a shootout in San Bernardino, Calif., Wednesday, Dec. 2, 2015. The scene followed a military-style attack that killed multiple people and wounded others at a California center that serves people with developmental disabilities, authorities said. (KTTV via AP)
SAN BERNARDINA, CA - DECEMBER 2: A search team goes door-to-door looking for the third suspect in a residential neighborhood after a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Marcus Yam/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: A California Highway Patrol officer stands with his weapon as authorities pursued the suspects in a shooting that occurred at the Inland Regional Center on December 2, 2015 in San Bernardino, California. Police continue to search for suspects in the shooting that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: A California Highway Patrol officer stands with his weapon as authorities pursued the suspects in a shooting that occurred at the Inland Regional Center on December 2, 2015 in San Bernardino, California. Police continue to search for suspects in the shooting that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: A San Bernadino Sheriff helicopter flys above a neighborhood as authorities pursue suspects of the shooting at the Inland Regional Center on December 2, 2015 in San Bernardino, California. Police continue to search for suspects in the shooting that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Officers swarm San bernardino Ave at Richardson Street near where suspects were shot in a black SUV December 2, 2015 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for suspects still at large. (Photo by Irfan Khan/Los Angeles Times via Getty Images)
Law enforcement officials with armored vehicles search an area near where police stopped a suspect SUV in San Bernardino, Calif., Wednesday, Dec. 2, 2015. The search followed a military-style attack that killed multiple people and wounded others at a California center that serves people with developmental disabilities, authorities said. (AP Photo/Chris Carlson)
Armored vehicles surround an SUV following a shootout in San Bernardino, Calif., Wednesday, Dec. 2, 2015. The scene followed a military-style attack that killed multiple people and wounded others at a California center that serves people with developmental disabilities, authorities said. (KNBC via AP) TV OUT
SAN BERNARDINO, CA - DECEMBER 2: Ambulances leave the scene of a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Gina Ferazzi / Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Police draw guns on San Bernardino Avenue while chasing suspects in an SUV December 2, 2015 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for suspects still at large. (Photo by Francine Orr/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Police draw guns on San Bernardino Avenue while chasing suspects in an SUV December 2, 2015 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for suspects still at large. (Photo by Francine Orr/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Police and emergency vehicles line Waterman Avenue in front of the Inland Regional Center in San Bernardino, scene of a mass shooting on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at large. (Photo by Luis Sinco/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Police and emergency vehicles line Waterman Avenue in front of the Inland Regional Center in San Bernardino, scene of a mass shooting on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at large. (Photo by Luis Sinco/Los Angeles Times via Getty Images)
Police at the scene of a shooting on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: Members of the FBI Joint Terrorism Task Force stand outside of a press conference regarding the shooting that occurred at the Inland Regional Center on December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by Sean M. Haffey/Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: Ambulances pull out of a staging area near the Inland Regional Center where a shooting occurred earlier in the day on December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by Sean M. Haffey/Getty Images)
A heavily armed officer sets up a perimeter near the site of a shooting that took place on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: San Bernardino County Sheriffs deputies respond to a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by David McNew/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: A San Bernardino County Sheriffs Department investigator responds to a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by David McNew/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Employees and other people are evacuated by bus from the site of a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by David McNew/Getty Images)
Police escort civilians away from the 1300 block of S. Waterman Street near the site of a shooting took place on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Police escort civilians away from the 1300 block of S. Waterman Street near the site of a shooting took place on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Armed Sheriff's department personel man a roadblock at Waterman Street near the site of a shooting took place on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
A swat team arrives at the scene of a shooting in San Bernardino, Calif. on Wednesday, Dec. 2, 2015. Police responded to reports of an active shooter at a social services facility. (Doug Saunders/Los Angeles News Group via AP) 
SAN BERNARDINO, CA - DECEMBER 2: Police and fire personnel secure the scene where a mass shooting occurred at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at large. (Photo by Gina Ferazzi / Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: San Bernardino police offices in SWAT gear secure the scene where a mass shooting occurred at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at large. (Photo by Gina Ferazzi / Los Angeles Times via Getty Images)
A crowd gathers behind police line near the scene of a shooting on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Photo courtesy: AP
Photo courtesy: AP

A couple embraces following a shooting that killed multiple people at a social services facility, Wednesday, Dec. 2, 2015, in San Bernardino, Calif. (David Bauman/The Press-Enterprise via AP)

People are evacuated by law enforcement agencies from the Inland Regional Center the scene of a shooting in San Bernardino, Calif. on Wednesday, Dec. 2, 2015. Police in San Bernardino, California, were responding to reports of an active shooter at a social services facility. There were reports of multiple victims, Lt. Rich Lawhead said Wednesday. (Doug Saunders/Los Angeles News Group via AP)
A first responder attends to a person outside a Southern California social services center in San Bernardino, where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KNBC via AP)
People are evacuated by law enforcement agencies from the Inland Regional Center the scene of a shooting in San Bernardino, Calif. on Wednesday, Dec. 2, 2015. Police in San Bernardino, California, were responding to reports of an active shooter at a social services facility. There were reports of multiple victims, Lt. Rich Lawhead said Wednesday. (Doug Saunders/Los Angeles News Group via AP)
First responders attend to people outside a Southern California social services center in San Bernardino, where one or more gunmen opened fire, shooting multiple people on Wednesday, Dec. 2, 2015. (KNBC via AP)

First responders gather outside a Southern California social services center in San Bernardino, Calif., where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KTTV via AP)

A woman holds her arm as first responders attend to people outside a Southern California social services center in San Bernardino, Calif., where one or more gunmen opened fire, shooting multiple people on Wednesday, Dec. 2, 2015. (KNBC via AP) 
This aerial view shows a Southern California social services center in San Bernardino, Calif., where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KTTV via AP)
In this aerial view, first responders gather on a nearby street corner, lower left, outside a Southern California social services center, upper right, in San Bernardino, Calif., where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KTTV via AP)
First responders gather on a nearby street corner as victims are treated outside a Southern California social services center in San Bernardino, Calif., where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KTTV via AP)
Law enforcement officials walk with weapons drawn outside a Southern California social services center in San Bernardino, Calif., where authorities said multiple people were shot Wednesday, Dec. 2, 2015. (KTTV via AP)
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Wearing black tactical gear and wielding assault rifles, Farook, a 28-year-old county restaurant inspector, and his wife, Tashfeen Malik, 27, sprayed as many as 75 rounds into a room at a social service center for the disabled, where Farook's co-workers had gathered for a holiday banquet Wednesday. Farook had attended the event but slipped out and returned in battle dress.

Four hours later and two miles away, the couple died in a furious gunbattle in which they fired 76 rounds, while 23 law officers unleashed about 380, police said.

On Thursday, Police Chief Jarrod Burguan offered a grim morning-after inventory that suggested Wednesday's bloodbath could have been far worse.

Witnesses describe the scene:

Witnesses of the San Bernardino Shooting Tell Their Stories

At the social service center, the couple left three rigged-together pipe bombs with a remote-control detonating device that apparently malfunctioned, and they had more than 1,600 rounds of ammunition remaining when police killed them in their rented SUV, Burguan said.

At a family home in the nearby town of Redlands, they had 12 pipe bombs, tools for making more, and over 3,000 additional rounds of ammunition, the chief said.

"We don't know if this was workplace rage or something larger or both," Attorney General Loretta Lynch said in Washington, echoing President Barack Obama. "We don't know the motivation."

Investigators are trying to determine whether Farook, who was Muslim, became radicalized — and, if so, how — and whether he was in contact with any foreign terrorist organization, said the U.S. intelligence official, who was not authorized to discuss the matter publicly and spoke on condition of anonymity.

The same official said Farook had been in touch on social media with extremists who were under FBI scrutiny.

Images of the community's reaction:

36 PHOTOS
San Bernardino Shooting, People on Scene, Mourning
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Attackers in California shooting had thousands of bullets
SAN BERNARDINO, CA - DECEMBER 3: A local outreach group prays with residents near the scene of an investigation where two suspects were gunned down during a shootout with police, December 3, 2015 in San Bernardino, California. A day earlier, the two suspects allegedly shot and killed 14 people at the Inland Regional Center in San Bernardino. (Photo by Gina Ferazzi/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 3: Redondo Police Officer Dan Richey carries a bouquet of flowers to deliver to a female shooting victim that grew up in Redondo Beach at the Arrowhead Regional Medical Center on December 3, 2015 in San Bernardino, California.A day earlier, the two suspects allegedly shot and killed 14 people and injured over 20 at the Inland Regional Center in San Bernardino. (Photo by Gina Ferazzi/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 03: A mourner cries as she brings flowers to a road block outside of the Inland Regional Center on December 3, 2015 in San Bernardino, California. Police continue to investigate a mass shooting at the Center that left at least 14 people dead and another 17 injured. (Photo by Justin Sullivan/Getty Images)
A woman identified as the fiancée of shooting victim (C-purple) is comforted by friends and Chaplain Steve Ballinger (L) as she leaves flowers on December 3, 2015, near the site of a mass shooting at the Inland Regional Center where 14 people were killed on December 2 in San Bernardino, California. Ballinger said the woman's fiancé died in the attack. AFP PHOTO/PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 3: Larry Jones, pastor of Cross over Outreach Church, Dr. Jeannetta Million, pastor of Victoria's Believers Church, and Arnold Morales, pastor of King of Glory Church bow their heads in prayers for the victims and those involved in the mass shootings at the Inland Regional Center, during a prayer vigil at Orange Show Road and Waterman Avenue December 3, 2015 in San Bernardino, California. Investigators are looking for a motive as to why Syed Rizwan Farook and Tashfeen Malik went on a shooting rampage that left 14 dead and at least 17 others wounded. (Photo by Marcus Yam/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 3: Local resident Katrina Venegas is close to tears as she has been kept away from her home which is directly in front of shooting scene where 2 suspects were gunned down driving a black SUV during a shootout with police on San Bernardino Avenue the day after the suspects allegedly shot and killed 14 people at the Inland Regional Center on December 3, 2015 in San Bernardino, California. She said her dog has been locked in the house alone since yesterday. (Photo by Gina Ferazzi/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 3: San Bernardino resident Lisa Gonzalez hugs Pastor Ernie Ceballos after he was helpful in getting the police to escort her back to her home on the same street where sheriff deputies investigate the scene where 2 suspects were gunned down during a shootout with police on San Bernardino Avenue the day after the suspects allegedly shot and killed 14 people at the Inland Regional Center on December 3, 2015 in San Bernardino, California. Gonzalez had left home briefly yesterday to go buy milk for her twin 3-year-olds. The shooting took place in front of her house while she was gone. She and her son, Santana Gonzalez,left, were not allowed back to their home so they spent the night in a hotel. Her husband was home with the children and wasn't allowed to leave the home. (Photo by Gina Ferazzi/Los Angeles Times via Getty Images)
People wait at a community center for a family member who was near a shooting that killed multiple people at a social services center, Wednesday, Dec. 2, 2015, in San Bernardino, Calif. (AP Photo/Jae C. Hong)
Jesus Gonzales, center left, who has been separated with his wife since Wednesday's shooting, is comforted by local church members including Jose Gomez, center right, Thursday, Dec. 3, 2015, in San Bernardino, Calif. Gonzales has been unable to get to his home due to a police shootout with suspects which took place in his neighborhood. (AP Photo/Jae C. Hong)
A group of local church members pray for residents who live in the neighborhood where Wednesday's police shootout with suspects took place, Thursday, Dec. 3, 2015, in San Bernardino, Calif. Multiple attackers opened fire on a banquet at a social services center for the disabled in San Bernardino on Wednesday, killing multiple people and sending police on a manhunt for suspects.(AP Photo/Jae C. Hong)
SAN BERNARDINA, CA - DECEMBER 2: Olivia Navarro waits to see her daughter after a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Marcus Yam/Los Angeles Times via Getty Images)
A woman, center, who survived a shooting rampage, talks to members of the media outside a community center after she reunited with her parents Wednesday, Dec. 2, 2015, in San Bernardino, Calif. Multiple attackers opened fire on a banquet at a social services center for the disabled in San Bernardino on Wednesday, killing multiple people and sending police on a manhunt for suspects. (AP Photo/Jae C. Hong)
SAN BERNARDINO, CA - DECEMBER 03: A group of men embrace in prayer outside the crime scene where the suspects in the shooting at the Inland Resource Center were killed on December 3, 2015 in San Bernardino, California. Police continue to investigate a mass shooting at the Inland Regional Center in San Bernardino that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
SAN BERNARDINO, CA - DECEMBER 02: Mayor of San Bernadino, California R. Carey Davis pauses during a press conference at City Hall regarding the shooting that took place inside the Inland Regional Center on December 2, 2015 in San Bernardino, California. Police continue to investigate the shooting that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
A woman who declined to give her name kisses her sister, center, a survivor of a shooting rampage that killed multiple people and wounded others as they reunite at a community center in San Bernardino, Calif., Wednesday, Dec. 2, 2015. (AP Photo/Jae C. Hong)
A man hugs a person who was near a shooting rampage at a social services center that killed multiple people and wounded others, Wednesday, Dec. 2, 2015, at a community center where family members gathered to pick up the survivors in San Bernardino, Calif. (AP Photo/Jae C. Hong)
SAN BERNARDINO, CA - DECEMBER 02: Mayor of San Bernadino, California R. Carey Davis speaks during a press conference at City Hall regarding the shooting that took place inside the Inland Regional Center on December 2, 2015 in San Bernardino, California.Police continue to investigate the shooting that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
Omar Riopedre embraces his wife Diana, who was in the Inland Regional Center when the mass shootings took place, as they leave the Rudy C. Hernandez Community Center in the San Bernardino on December 2, 2015. A man and a woman suspected of carrying out a deadly shooting at a center for the disabled in California were killed in a shootout with police, while a third person was detained, police said. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
David Bowditch, assistant director in charge of the FBI LA field office, talks to the media near the the site of a mass shooting on Wednesday, Dec. 2, 2015 in San Bernardino, Calif. One or more gunmen opened fire Wednesday at a Southern California social services center, shooting several people as others locked themselves in their offices, desperately waiting to be rescued by police, witnesses and authorities said. Authorities said the shooting rampage killed multiple people and wounded others. (AP Photo/Chris Carlson)
San Bernardino Police Chief Jarrod Burguan, right, talks to the media near the the site of a mass shooting on Wednesday, Dec. 2, 2015, in San Bernardino, Calif. One or more gunmen opened fire Wednesday at a Southern California social services center, shooting several people as others locked themselves in their offices, desperately waiting to be rescued by police, witnesses and authorities said. Authorities said the shooting rampage killed multiple people and wounded others. (AP Photo/Chris Carlson)
People who were near a deadly shooting at a social services center that killed multiple people arrive at at a community center in San Bernardino, Calif., Wednesday, Dec. 2, 2015. (AP Photo/Jae C. Hong)
SAN BERNARDINA, CA - DECEMBER 2: Luis Gutierrez gets emotional as he talks about his wife after a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Marcus Yam/Los Angeles Times via Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Marie Cabrera, Sonya Gonzalez and Christine Duran, all of San Bernardino, pray after a mass shooting at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at-large. (Photo by Rick Loomis/Los Angeles Times via Getty Images)
People evacuated from the Inland Regional Center walk from busses into The Rock Church and World Outreach Center during the aftermath of a mass shooting at the facility on December 2, 2015 in San Bernardino, California. One or more gunmen opened fire inside a center for the disabled in killing at least 14 people and wounding the same number before fleeing the scene, officials said. AFP PHOTO / PATRICK T. FALLON / AFP / Patrick T. Fallon (Photo credit should read PATRICK T. FALLON/AFP/Getty Images)
A woman wipes her tears at a community center where family members are gathering to pick up survivors after a shooting rampage that killed multiple people and wounded others at a social services center in San Bernardino, Calif., Wednesday, Dec. 2, 2015. (AP Photo/Jae C. Hong)
Teresa Hernandez, facing camera, is comforted by a woman as she arrives at a social services center in San Bernardino, Calif., where one or more gunmen opened fire, shooting multiple people on Wednesday, Dec. 2, 2015. (AP Photo/Jae C. Hong)
SAN BERNARDINO, CA - DECEMBER 2: Employees and other people are evacuated by bus from the site of a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to 3 suspects who are still at large. (Photo by David McNew/Getty Images)
Two women embrace at a community center where family members are gathering to pick up survivors after a shooting rampage that killed multiple people and wounded others at a social services center in San Bernardino, Calif., Wednesday, Dec. 2, 2015. (AP Photo/Jae C. Hong)
SAN BERNARDINO, CA - DECEMBER 2: Employees and other people are evacuated by bus from the site of a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by David McNew/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2: Employees and other people are evacuated by bus from the site of a mass shooting at the Inland Regional Center December 2, 2015 in San Bernardino, California. Multiple fatalities were reported as police search for up to three suspects who are still at large. (Photo by David McNew/Getty Images)
Police escort civilians away from the 1300 block of S. Waterman Street near the site of a shooting took place on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Survivors are evacuated from the scene of a shooting on December 2, 2015 in San Bernardino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Survivors are evacuated from the scene of a shooting under police and sheriff's escort on December 2, 2015 in San Bernadino, California. One or more gunman opened fire inside a building in San Bernardino in California, with reports of 20 victims at a center that provides services for the disabled. Police were still hunting for the shooter, saying one to three possible suspects were involved. Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, located about an hour east of Los Angeles, as police warned residents away. AFP PHOTO / FREDERIC J. BROWN / AFP / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
SAN BERNARDINO, CA - DECEMBER 2, 2015: Evacuated workers pray in a circle on the San Bernardino Golf Course across the street where a mass shooting occurred at the Inland Regional Center on December 2, 2105 in San Bernardino, California. Multiple fatalities and injuries were reported as police search for up to three suspects who are still at large. (Photo by Gina Ferazzi / Los Angeles Times via Getty Images)
Two women comfort each other near the scene of a shooting outside a Southern California social services center in San Bernardino, Calif., where one or more gunmen opened fire, shooting multiple people on Wednesday, Dec. 2, 2015. (KNBC via AP)
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The second U.S. official said the FBI was treating the attack as a potential act of terror but had reached no conclusion that it was. The official said Farook's contacts online did not involve any significant players on the agency's radar and dated back some time, and there was no immediate indication of any surge in communication ahead of the shooting.

The official cautioned that such contact by itself doesn't mean someone is a terrorist.

Rita Katz, director of SITE Intelligence Group, an organization that tracks and analyzes extremists, said it hasn't found any connection so far between Farook and jihadi groups. But she also said that some of Farook's social media posts seem to have been deleted before the attack.

Wednesday's rampage was the nation's deadliest mass shooting since the Newtown, Connecticut, school tragedy three years ago that left 26 children and adults dead.


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Twenty-one people were injured before the day was out in San Bernardino, a Southern California city of 214,000, including two police officers, authorities said. Two of the wounded remained in critical condition.

Authorities said the attack was carefully planned.

"There was obviously a mission here. We know that. We do not know why. We don't know if this was the intended target or if there was something that triggered him to do this immediately," David Bowdich, assistant director of the FBI's Los Angeles office, said as the bureau took over the investigation.

Farook has no known criminal record, Burguan said. He was born in Chicago to a Pakistani family, raised in Southern California and worked at San Bernardino County's Department of Public Health for five years, according to authorities and acquaintances. The Saudi Embassy said he traveled to Saudi Arabia in the summer of 2014 for nine days.

As for Malik, she came to the U.S. in July 2014 on a Pakistani passport and a fiancée visa, authorities said. To get the visa, immigrants submit to an interview and biometric and background checks — screening intended to identify anyone who might pose a threat.

They were married on Aug. 16, 2014, in nearby Riverside County, according to their marriage license. Both listed their religion as Muslim.

The couple had a 6-month-old daughter who they dropped with relatives Wednesday morning before the shooting.

Adam Lankford, a criminal justice professor at the University of Alabama, said his review of mass public shootings in the U.S. indicates this is the first one in recent history to involve a male-female team.

Federal authorities said Farook legally bought two handguns used in the massacre and their two assault rifles were legally bought by someone else. Authorities did not say how the rifles got into the attackers' hands.

Two weeks ago, Farook and one of the co-workers he killed, 52-year-old Nicholas Thalasinos, had a heated conversation about Islam, according to Kuuleme Stephens, a friend of the victim.

Stephens said she happened to call Thalasinos while he was talking with Farook at work. She said Thalasinos told her Farook "doesn't agree that Islam is not a peaceful religion."

As for workplace conflicts, co-worker Patrick Baccari said that until the rampage, Farook showed no signs of unusual behavior and was a reserved young man.

Baccari said he was sitting at the same banquet table as Farook before Farook suddenly disappeared, leaving his coat on his chair. Baccari was in the bathroom when the shooting started; he suffered minor wounds from shrapnel slicing through the wall.

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Associated Press writers Brian Melley, John Antczak, Christopher Weber, Christine Armario and Gillian Flaccus in Los Angeles; Ken Dilanian, Eric Tucker and Tami Abdollah in Washington; Amy Taxin and Kimberly Pierceall in Redlands; Alina Hartounian in Phoenix; Michael Sisak in Philadelphia; and Holbrook Mohr in Jackson, Mississippi, contributed to this story. Pritchard reported from Los Angeles.

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