Moving from house to house, a US Army sergeant opened fire on Afghan villagers as they slept, killing 16 people – mostly women and children – in an attack that reignited fury at the US presence following a wave of deadly protests over Americans burning Korans.
The attack threatened the deepest breach yet in US-Afghan relations, raising questions both in Washington and Kabul about why American troops are still fighting in Afghanistan after 10 years of conflict and the killing of Osama bin Laden.
The deaths, one of the worst atrocities committed by US forces during the Afghan war, came amid deepening public outrage spurred by last month’s Koran burnings and an earlier video purportedly showing US Marines urinating on dead Taliban militants.
The Koran burnings sparked weeks of violent protests and attacks that left some 30 Afghans dead, despite an apology from President Barack Obama.
Six US service members were also killed by their fellow Afghan soldiers, although the tensions had just started to calm down.
According to US and Afghan officials, yesterday’s attack began around 3am in two villages in Panjwai district, a rural region outside Kandahar that is the cradle of the Taliban and where coalition forces have fought for control for years.
The villages are about 500 yards from a US base in a region that was the focus of Mr Obama’s military surge strategy in the south starting in 2009.
Villagers described cowering in fear as gunshots rang out as a soldier roamed from house to house firing on those inside.
They said he entered three homes in all and set fire to some of the bodies. Eleven of the dead were from a single family, and nine of the victims were children.
US officials said the shooter, identified as an Army staff sergeant, acted alone, leaving his base in southern Afghanistan and opening fire on sleeping families in two villages.
Initial reports indicated he returned to the base after the shooting and turned himself in. He was in custody at a Nato base in Afghanistan.
The suspect, from Joint Base Lewis-McChord, Washington, was assigned to support a special operations unit of either Green Berets or Navy Seals engaged in a village stability operation, said a US official.
Such operations are among Nato’s best hopes for transitioning out of Afghanistan, pairing special operations troops with villagers chosen by village elders to become essentially a sanctioned, armed neighbourhood watch.
Some residents said they believed there were multiple attackers, given the carnage.
“One man can’t kill so many people. There must have been many people involved,” Bacha Agha of Balandi village said.
“If the government says this is just one person’s act we will not accept it. ... After killing those people they also burned the bodies.”
In a statement, Afghan president Hamid Karzai left open the possibility of more than one shooter.
He initially spoke of a single US gunman, then referred to “American forces” entering houses.
The statement quoted a 15-year-old survivor named Rafiullah, who was shot in the leg, as telling Mr Karzai in a phone call that “soldiers” broke into his house, woke up his family and began shooting them.
“This is an assassination, an intentional killing of innocent civilians and cannot be forgiven,” Mr Karzai said.
Mr Obama phoned the Afghan leader to express his shock and sadness, and offered condolences to the grieving families and to the people of Afghanistan.
In a statement released by the White House, Mr Obama called the attack “tragic and shocking” and not representative of “the exceptional character of our military and the respect that the United States has for the people of Afghanistan”.
He vowed “to get the facts as quickly as possible and to hold accountable anyone responsible”.
The violence over the Koran burnings had already spurred calls in the US for a faster exit strategy from the 10-year-old Afghan war.
Mr Obama even said recently that “now is the time for us to transition”.
But he also said he had no plan to change the current timetable that has Afghans taking control of security countrywide by the end of 2014.
In the wake of the Koran burnings, the top US commander in Afghanistan, General John Allen, visited troops at a base that was attacked last month and urged them not to give in to the impulse for revenge.
The tensions between the two countries had appeared to be easing as recently as Friday, when the two governments signed a memorandum of understanding about the transfer of Afghan detainees to Afghan control – a key step toward an eventual strategic partnership to govern US forces in the country.
Now, another wave of anti-American hatred could threaten the entire future of the mission, fuelling not only anger among the Afghans whom the coalition is supposed to be defending but also encouraging doubts among US political figures that the long and costly war is worth the sacrifice in lives and treasury.
Gen Allen offered his regret and “deepest condolences” to the Afghan people for the shootings and vowed to make sure that “anyone who is found to have committed wrongdoing is held fully accountable”.
“This deeply appalling incident in no way represents the values of Isaf and coalition troops or the abiding respect we feel for the Afghan people,” Gen Allen said in a statement, using the abbreviation for Nato’s International Security Assistance Force.
In Panjwai district, grieving residents tried to make sense of why they were targeted.
“No Taliban were here. No gunbattle was going on,” cried out one woman, who said four people were killed in the village of Alokzai, all members of her family.
“We don’t know why this foreign soldier came and killed our innocent family members. Either he was drunk or he enjoyed killing civilians.”
The other 12 dead were from Balandi village, said Samad Khan, a farmer who lost all 11 members of his family, including women and children.
Mr Khan was away from the village when the attack occurred and returned to find his family members shot and burned. One of his neighbours was also killed, he said.
“This is an anti-human and anti-Islamic act,” Mr Khan said. “Nobody is allowed in any religion in the world to kill children and women.”
One woman opened a blue blanket with pink flowers to reveal the body of her two-year-old child, who was wearing a blood-soaked shirt.
“Was this child Taliban? There is no Taliban here,” said Gul Bushra. The Americans “are always threatening us with dogs and helicopters during night raids”.
Dozens of villagers crowded the streets as minibuses and lorries carried away the dead to be washed for burial. One man used the edge of his brown shawl to wipe away tears.
Officials wearing white plastic gloves picked up bullet casings from the floor of a house and put them in a plastic bag.