US staff sergeant kills 16 Afghan civilians, officials say Mammon Durrani / AFP - Getty Images A villager on Sunday points to where a family was allegedly shot in their home by a U.S. soldier in Alkozai, a village in Afghanistan's Kandahar province. Updated at 3:15 p.m. ET: KANDAHAR, Afghanistan -- A U.S. service member shot dead at least 15 members of two Afghan families as well as a 16th person before turning himself in, officials said Sunday. U.S. officials said the soldier was a staff sergeant. Some witnesses said more than one soldier was involved, but Afghan President Hamid Karzai in a statement cited only one shooter in what he called "an assassination," adding that nine of the dead were children, and three were women. The detained soldier, who has yet to be identified, reportedly left his base in the early hours Sunday and went to two villages just a few hundred yards away. He then opened fire on Afghan civilians sleeping in their homes, Minister of Border and Tribal Affairs Asadullah Khalid told Reuters. The service member entered three homes in the villages in Kandahar province, he said. Twelve of the dead were from Balandi, said Samad Khan, adding that 11 were from his family, including women and children. Khan was away from the village when the incident occurred. One of his neighbors was also killed, he said. "This is an anti-human and anti-Islamic act," said Khan. Nobody is allowed in any religion in the world to kill children and women. Ahmad Nadeem / Reuters Afghan soldiers keep watch at a U.S. military base Sunday as nearby residents gather following the killing of civilians in a rural area of Kandahar province. Khan demanded that Karzai punish the American shooter. "Otherwise we will make a decision," said Khan. He should be handed over to us. The U.S.-led NATO mission in Afghanistan said the soldier being held would remain in its custody. Four people reportedly killed in the neighboring village were also from a single family, said a female relative who was shouting in anger. She did not give her name because of the conservative nature of local society. No Taliban were here. No gun battle was going on," said the woman. We don't know why this foreign soldier came and killed our innocent family members. Either he was drunk or he was enjoying killing civilians. Military discipline and the 'command climate' in Afghanistan comes into question after a U.S. soldier allegedly opened fire on sleeping civilians in Kandahar province. NBC's Jim Miklaszewski reports. The BBC reported that the soldier was thought to have suffered a breakdown. Earlier, Afghanistan's defense ministry told Reuters that "coalition forces" killed civilians in the shooting spree. NATO did not immediately comment on the report, which implied that there had been more than one attacker. American and NATO officials apologized for Sunday's shootings. "I offer my condolences to the families and loved ones of those who lost their lives, and to the people of Afghanistan, who have endured too much violence and suffering," President Barack Obama, who also spoke with Karzai, said in a statement. This incident is tragic and shocking, and does not represent the exceptional character of our military and the respect that the United States has for the people of Afghanistan. MSNBC military analyst Gen. Barry McCaffrey (Ret.) says the alleged shooting of Afghan civilians by a US soldier is a 'further unraveling' of relations between the US and Afghanistan. NATO, meanwhile, called the attack "appalling" and said it was in no way part of its authorized activities. "An investigation is already underway and every effort will be made to establish the facts and hold anyone responsible to account," Lt. Gen. Adrian Bradshaw, deputy commander of the NATO-led International Security Assistance Force, said in a statement. Civilian casualties have been a major source of friction between Karzai's government and NATO forces in Afghanistan. The killings happened in Panjwayi district, about 22 miles west of Kandahar City. The district is considered the spiritual home of the Taliban and has been a hive of insurgent activity in recent years. Anti-American sentiment is running high in Afghanistan and it may deepen once news of the shooting spreads.