FBI says investigating California massacre as act of terrorism

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Official: FBI Investigating San Bernardino Shooting As Act Of Terrorism


The FBI is investigating this week's massacre in which a married couple killed 14 people in California as an "act of terrorism," an official said on Friday, saying the female shooter had pledged allegiance to a leader of the militant group Islamic State.

Tashfeen Malik, 27, a native of Pakistan who lived in Saudi Arabia for more than 20 years, and her U.S.-born husband, Syed Rizwan Farook, 28, were killed in a shootout with police hours after the Wednesday massacre during a holiday party at the Inland Regional Center social services agency in San Bernardino, about 60 miles (100 km) east of Los Angeles. The attack was the deadliest mass shooting the United States has experienced in three years.

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San Bernardino Shooting, People on Scene, Mourning
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FBI says investigating California massacre as act of terrorism
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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Malik had pledged allegiance to Islamic State leader Abu Bakr al-Baghdadi in an online post, David Bowdich, assistant director of the Federal Bureau of Investigation's Los Angeles office, said at a news conference.

That finding could be a "game changer" in the investigation, two U.S. government sources told Reuters. Another source cautioned there was no indication of evidence that Islamic State "even knew" who the shooters were.

"Based on the information and the facts as we know them, we are now investigating these horrific acts as an act of terrorism," Bowdich said.

SEE MORE: California massacre shooter pledged allegiance to ISIS: CNN

Asked about a reported Facebook post by Malik on the day of the attack pledging loyalty to Islamic State, Bowdich said, "Yes, there was a pledge of allegiance."

Investigators have determined that the Malik and Farook engaged in extensive planning before the attack, he said.

Bowdich also said the FBI also was examining crushed cellphones found near the shooting scene and had established that there were "telephonic connections" between the couple and other people of interest in FBI probes.

The couple had two assault-style rifles, two semi-automatic handguns, 6,100 rounds of ammunition and 12 pipe bombs in their home or with them when they were killed, officials said.

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San Bernardino active shooter, scene, police operations
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FBI says investigating California massacre as act of terrorism
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)
Graphic locates mass shooting in San Bernardino, California.; 2c x 5 inches; 96.3 mm x 127 mm;
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Bowdich said the couple may have been planning an additional attack, Bowdich said.

Farook, born in Illinois to Pakistani immigrant parents, worked as an inspector for the San Bernardino County Department of Environment Health, the agency whose holiday party he and Malik attacked on Wednesday.

Investigators are looking into a report that Farook had an argument with a co-worker who denounced the "inherent dangers of Islam" prior to the shooting, a U.S. government source said.

While the attack may have been inspired by Islamic State, there is no evidence that it was directed by the militant group, U.S. government sources said. Islamic State, which has seized large parts of Syria and Iraq, took claim for the Nov. 13 attacks in Paris in which gunmen and suicide bombers killed 130.

The couple's landlord in the town of Redlands opened their townhouse to media on Friday, leading to a flurry of reporters and camera crews surveying the scene. The landlord later asked media to leave.

The FBI's search of the home turned up no evidence to suggest they had been working with any foreign militant group, a U.S. government source said.

WATCH: FBI: No sign California shooters part of larger group:

FBI: "No Sign California Shooters Part of Larger Group

PROBE EXTENDS TO PAKISTAN

Pakistani intelligence officials have contacted Malik's family in her homeland as part of the investigation, a family member said.

"I only found out about this tragedy today when some intelligence officials contacted me to ask me about my links with Tashfeen," Malik's uncle, Javed Rabbani, said in an interview. "I had heard in the news that this tragedy had taken place but I could never even imagine that it would be someone from my family. Of course, we are in shock."

He said his brother, Malik's father, had become considerably more conservative since moving with his family to Saudi Arabia a quarter century ago.

Tashfeen Malik had not come to the attention of authorities while living in Saudi Arabia, according to a source close to the Saudi government. She had moved back to Pakistan five or six years ago to study pharmacy, Pakistani officials said.

Christian Nwadike, who worked with Farook for five years, told CBS that his co-worker had been different since he returned from Saudi Arabia.

"I think he married a terrorist," Nwadike said.

Twenty-one people were wounded in the attack, the worst gun violence in the nation since the December 2012 shooting at Sandy Hook Elementary School in Newtown, Connecticut.

Farook had not been under surveillance by the FBI or any other law enforcement agency, Bowdich said, adding that there was no evidence that additional threats lingered following the shooting.

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