Two American service members were killed fighting the Taliban near the northern city of Kunduz on Thursday, the U.S. military said amid reports that air strikes called in to protect the troops had caused heavy civilian casualties.
Although the U.S. military gave no details, Afghan officials said there had been heavy fighting overnight about 5 km (3 miles) from the city center, which Taliban fighters succeeded in entering as recently as last month, and air strikes had caused many casualties.
There were angry protests by civilians who brought the bodies of at least 16 dead into Kunduz, Mafuzullah Akbari, a police spokesman said. Some reports put the death toll higher but there was no immediate official confirmation.
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29 photos of the past 15 years at war in Afghanistan
29 photos of the past 15 years at war in Afghanistan
** FOR USE AS DESIRED, PHOTOS OF THE DECADE ** FILE - Osama bin Laden is seen at an undisclosed location in this television image broadcast in this Oct. 7, 2001 file photo. Bin Laden praised God for the Sept. 11 terrorist attacks and swore America "will never dream of security" until "the infidel's armies leave the land of Muhammad," in a videotaped statement aired after the strike launched Sunday by the U.S. and Britain in Afghanistan. Graphic at top right reads "Exclusive to Al-Jazeera." At bottom right is the station's logo which reads "Al-Jazeera." At top left is "Recorded." Bottom left is "Urgent news." At bottom center is "Osama bin Laden, Leader of the al-Qaida." (AP Photo/Al Jazeera, File)
The United States and Britain on October 7, 2001 launched a first wave of air strikes against Afghanistan and President George W. Bush said the action heralded a "sustained, comprehensive and relentless" campaign against terrorism. Eyewitnesses said they saw flashes and heard explosions over the Afghan capital of Kabul in the first phase of what the United States has said will be a protracted and wide-ranging war against terrorism and the states that support it. The attack had been prepared since the September 11 suicide attacks on the United States that killed around 5,600 people. A U.S. Air force B-52 bomber drops a load of M117 750-pound bombs over a bombing range in the United States in this undated file photo.B-52s, B-1 and B-2 stealth bombers are some of the aircraft that were reportedly used in the attacks on Afghanistan. REUTERS/USAF-Handout KM/HB
Mohammed Anwar, left, and an unidentied boy in Kabul, Afghanistan display pieces of shrapnel from bombs dropped Monday morning, Oct. 8, 2001. The U.S. and Britain hit Afghanistan and key installations of the Taliban regime with cruise missiles Sunday night for harboring suspected terrorist Osama bin Laden. Many residents of Afghanistan seem unfazed by the bombing after living in war like conditions for more than 20 years. (AP Photo/Amir Shah)
Two Northern Alliance soldiers watch as the dust and smoke rises after
explosions in Taliban positions on Kalakata hill, near the village of
Ai-Khanum in northern Afghanistan, November 1, 2001. The Pentagon said
on Wednesday B-52s dropped heavy loads of bombs, a tactic known as
carpet bombing, on Taliban troops north of Kabul as a result of
improved tergeting intelligence, partly from U.S. special forces on the
ground. REUTERS/Vasily Fedosenko
U.S. Marine PV2 Eileen M. Schnetzko stands on guard at Bagram airport,
March 2, 2002. U.S. troops are based at Bagram, north of Kabul. There
are some 4,000 U.S. troops based in Afghanistan as part of the
international war against terrorism. REUTERS/Mario Laporta REUTERS
Land mine detectors stand by as a U.S. army soldier, right, maneuvers Hermes the robot into a cave to detect mines, traps, and other unexploded ordnance as well as weapons or equipment possibly hidden by Taliban or al-Qaida fugitives in the eastern border town of Qiqay, Afghanistan, Monday, July 29, 2002. The war in Afghanistan is the first time robots are being used by the U.S. military as tools for combat. Proponents of the robots believe sending them first into caves, buildings or other dark areas will help prevent U.S. casualties. (AP Photo/Wally Santana)
Afghan villagers watch as US soldiers from the 82nd airborne Bravo Company search a house for suspected Taliban and al-Qaida forces in the central part of the Baghran river valley during the finishing stages of "Operation Viper" in Helmand Province, southern Afghanistan on Monday Feb. 24, 2003. Suspected enemy fighters were spotted taking ambush positions in the area a few weeks ago by US troops as they went on patrol as part of the ongoing war against terrorism. (AP Photo/Aaron Favila, Pool)
A U.S. special forces soldier (L) watches while Afghan militia wait in
line to turn in their weapons at a military base in Kunduz, Afghanistan
October 22, 2003. A long-awaited U.N.-sponsored project to disarm,
demobilise and reintegrate 100,000 soldiers across Afghanistan was
under way in the north, a key step to bringing eventual peace to this
war-torn country. The "New Beginnings Programme," which lets soldiers
exchange their weapons for jobs, began in the northern province of
Kunduz this week. REUTERS/Richard Vogel/Pool
A Chinook helicopter hovers over U.S. troops in the village of Jegdelic, about 90 km (56 miles) southwest of Kabul, Afghanistan, in this picture taken on December 24, 2004. A U.S. military helicopter carrying up to 20 American troops crashed during an anti-guerrilla mission in eastern Afghanistan on Tuesday, U.S. officials said. The fate of those on board was not immediately known. Picture taken December 24, 2004. REUTERS/Ahmad Masood Am/mk BEST QUALITY AVAILABLE
A U.S. soldier inspects a wedding car at a check point in a crossroad near Bagram air base and detention center, north of Kabul, Afghanistan, Tuesday, July 12, 2005. Four suspected Arab terrorists who escaped from the heavily guarded U.S. military detention facility in Afghanistan are "a threat to the global war on terrorism," an American military spokesman said Tuesday, as a manhunt for them entered its second day. (AP Photo/Tomas Munita)
U.S. Secretary of Defense Donald H. Rumsfeld, center, presents a medal of valor to Sgt. Kenneth Stover, left, as soldiers watch from a rooftop during a medal ceremony in Khandahar, Afghanistan Thursday, Dec. 22, 2005. Rumsfeld arrived unannounced in Baghdad on Thursday to hold talks with U.S. commanders and assess the next phase of U.S. troop deployments in Iraq. (AP Photo/Jim Young, Pool)
US soldiers have lunch at the shopping area of the Kandahar military base, south Afghanistan, Wednesday, Aug 2, 2006. Afghanistan is wracked by its deadliest spate of violence since U.S.-led forces toppled the Taliban regime in late 2001 for hosting Osama bin Laden. More than 900 people _ mainly militants _ have been killed since May. (AP Photo/Rodrigo Abd)
An Afghan boy looks at U.S. soldiers as they patrol a village near the town of Makkor, southwest of Kabul April 20, 2007. REUTERS/Goran Tomasevic (AFGHANISTAN)
A U.S. soldier works with a shovel as a vehicle is stuck in mud, some 70km south of Ghazni, southeastern Afghanistan April 23, 2007. REUTERS/Goran Tomasevic (AFGHANISTAN)
British and a U.S. soldiers control the crowd during medical assistance in Kabul February 26, 2008. U.S. and British troops provided medical assistance worth of $50,000 to the Afghan locals in Kabul on Tuesday. REUTERS/Ahmad Masood (AFGHANISTAN)
Sgt. William Olas Bee, a U.S. Marine from the 24th Marine Expeditionary Unit, has a close call after Taliban fighters opened fire near Garmsir in Helmand Province of Afghanistan, May 18, 2008.
REUTERS/Goran Tomasevic (AFGHANISTAN)
U.S. Secretary of Defense Robert Gates (L) and U.S. Army General David McKiernan, the top U.S. and NATO Commander in Afghanistan (R) listen to Afghan governors and local officials during their visit to Forward Operating Base Airborne in the mountains of Wardak Province, Afghanistan, May 8, 2009. Gates on May 11, 2009 replaced the top U.S. and NATO commander in Afghanistan, U.S. Army General David McKiernan, less than a year after he took over the war effort there. Gates said he asked for McKiernan's resignation and recommended Army Lieutenant General Stanley McChrystal, a former commander of special operations forces, to take over command of 45,000 U.S. troops and about 32,000 other troops from non-U.S. NATO countries. REUTERS/Jason Reed (AFGHANISTAN MILITARY POLITICS)
U.S. soldiers of the 2-12 Infantry, 4th Brigade prepare to tow a broken-down improvised explosive device (IED) detecting Huskie vehicle during a patrol in the Pesh Valley in Afghanistan's Kunar Province July 30, 2009. REUTERS/Tim Wimborne (AFGHANISTAN CONFLICT)
U.S. soldiers kneel during a memorial ceremony for Captain Daniel Whitten and Private First Class Zachary Lovejoy from Charlie Company, 4th Brigade combat team,1-508, 82nd Parachute Infantry Regiment at the Remote Sweeney FOB in Zabul province, southern Afghanistan, February 8, 2010. CPT Whitten from Grimes, Iowa, and PFC Lovejoy from Albuquerque, New Mexico, were killed by an IED on February 2. when on patrol in southern Afghanistan.
REUTERS/Baz Ratner (AFGHANISTAN - Tags: CIVIL UNREST CONFLICT MILITARY)
Canadian soldiers play table football under flashlights at a military outpost near the village of Bazaar e Panjwaii, in the Panjwaii district of Kandahar province August 8, 2010. REUTERS/Bob Strong (AFGHANISTAN - Tags: CONFLICT MILITARY)
U.S. Army medic Staff Sergeant Rahkeem Francis with Charlie Company, 6-101 Combat Aviation Brigade, 101st Airborne Division, treats an Afghan boy with a broken leg onboard a medevac helicopter near the town of Marjah in Helmand Province, August 19, 2010. REUTERS/Bob Strong (AFGHANISTAN - Tags: CONFLICT MILITARY POLITICS)
U.S. Army soldiers from the 2nd Platoon, B battery 2-8 field artillery, fire a howitzer artillery piece at Seprwan Ghar forward fire base in Panjwai district, Kandahar province southern Afghanistan, June 12, 2011. REUTERS/Baz Ratner (AFGHANISTAN - Tags: CONFLICT MILITARY IMAGES OF THE DAY POLITICS)
An Afghan shepherd walks with a flock of sheep past a U.S. Marines armored vehicle of the Weapons Company, 1st Battalion, 3rd Marines outside the Camp Gorgak in Helmand province, southern Afghanistan July 5, 2011. REUTERS/Shamil Zhumatov (AFGHANISTAN - Tags: POLITICS MILITARY ANIMALS IMAGES OF THE DAY)
First Sergeant Mac Miller from Comanche Troop 3rd Squadron 4th Cavalry lift weights as he exercises in Forward Operating Base Connolly in Nangarhar province, eastern Afghanistan, March 3, 2012. Picture taken March 3, 2012. REUTERS/Erik De Castro (AFGHANISTAN - Tags: MILITARY CONFLICT)
A U.S. Army soldier and a member of the Afghan Uniform Police arm wrestle prior to a joint patrol near Command Outpost AJK (short for Azim-Jan-Kariz, a near-by village) in Maiwand District, Kandahar Province, Afghanistan, January 28, 2013. REUTERS/Andrew Burton (AFGHANISTAN - Tags: POLITICS CIVIL UNREST MILITARY SOCIETY TPX IMAGES OF THE DAY)
A U.S. service member takes a "selfie" as U.S. President Barack Obama shakes hands with troops after delivering remarks at Bagram Air Base in Kabul, May 25, 2014. Obama, on a visit to Afghanistan, said on Sunday his administration would likely announce soon how many troops the United States will keep in the country, as it winds down its presence after nearly 13 years of war. REUTERS/Jonathan Ernst (AFGHANISTAN - Tags: POLITICS MILITARY)
Afghan children gesture at U.S. soldiers from Grim Company of the 3rd Cavalry Regiment as they stand guard near an Afghan police checkpoint during a mission near Forward Operating Base Fenty in the Nangarhar province of Afghanistan December 19, 2014. REUTERS/Lucas Jackson (AFGHANISTAN - Tags: CIVIL UNREST POLITICS MILITARY CONFLICT)
U.S. soldiers attend to a wounded soldier at the site of a blast in Kabul, Afghanistan June 30, 2015. At least 17 people were wounded in a suicide bomb attack on NATO troops as their truck convoy passed down the main road running between Kabul's airport and the U.S. embassy, police and health ministry officials said. REUTERS/Omar Sobhani TPX IMAGES OF THE DAY
A U.S. soldier keeps watch at the site of an explosion in Kabul, Afghanistan January 4, 2016. A large explosion struck close to Kabul airport on Monday, causing at least 10 casualties near to the area where a suicide bomber blew himself up earlier in the day in the latest in a series of attacks in the Afghan capital over the past week. REUTERS/Omar Sobhani
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"The service members came under fire during a train, advise and assist mission with our Afghan partners to clear a Taliban position and disrupt the group's operations in Kunduz district," the U.S. military said in a statement.
In a separate statement, the NATO-led Resolute Support mission confirmed that air strikes had been carried out in Kunduz to defend "friendly forces under fire".
"All civilian casualty claims will be investigated," it said.
In a statement, the Taliban said American forces were involved in a raid to capture three militant fighters when they came under heavy fire. An air strike hit the village where the fighting was taking place, killing many civilians.
The deaths underline the precarious security situation around Kunduz, which Taliban fighters came close to over-running last month, a year after they briefly captured the city in their biggest success in the 15-year long war.
While the city itself was secured, the insurgents control large areas of the surrounding province.
The U.S. military gave no details on the identity of the two personnel who were killed or what units they served with and there was no immediate detailed comment on the circumstances of their deaths.
Although U.S. combat operations against the Taliban largely ended in 2014, special forces units have been repeatedly engaged in fighting while providing assistance to Afghan troops.
Masoom Hashemi, deputy police chief in Kunduz province, said police were investigating to try to determine if any of the dead were linked to the Taliban.
Thousands of U.S. soldiers remain in Afghanistan as part of the NATO-led Resolute Support training and assistance mission and a separate counterterrorism mission.
The deaths come a month after another U.S. service member was killed on an operation against Islamic State fighters in the eastern province of Nangarhar.
Afghan forces, fighting largely on their own since the end of the international combat mission, have suffered thousands of casualties, with more than 5,500 killed in the first eight months of 2016.
(Additional reporting by Hamid Shalizi; Writing by James Mackenzie; Editing by Simon Cameron-Moore, Robert Birsel)