KABUL, Afghanistan -- The clusters of bodies heaped in a rural Kandahar hamlet have given rise to the inevitable question: Are U.S.-Afghan relations now too tainted for the nations to move ahead as allies in this war?
On Sunday, a lone American serviceman slipped away from his base in southern Afghanistan before dawn and went on a methodical house-to-house shooting spree in a nearby scatter of Afghan homes, killing 16 people as they slept, nearly all of them women and children, according to Afghan officials who visited the scene.
The NATO force said the assailant was in military custody, having surrendered upon his return to base, and acknowledged that he had inflicted an unspecified number of casualties during the shooting spree that began about 3 a.m. in the Panjwayi district of Kandahar province.
A senior U.S. military officer in Washington described the shooter as an enlisted soldier but did not say what unit he was assigned to.
The major U.S. Army unit in the area, according to the military, is the 1st Stryker Brigade of the 25th Infantry Division. But there are multiple other smaller units.
President Barack Obama, in a statement, expressed "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."
"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."
Other U.S. officials called for calm and warned of potential reprisals against Americans in Afghanistan. Angry villagers in Panwayi carried some of the corpses to the U.S. base from which the assailant had come, and military installations across the country, together with Western embassies and foreign organizations, braced for the possibility of mass protests.
The Taliban movement referred to the killings as an "act of genocide." Afghan President Hamid Karzai called the shootings "intentional killings" and demanded an explanation from the American administration.
The incident, by far the worst known atrocity of the 10-year war to be deliberately carried out by a single Western soldier, represents a stunning new setback to U.S.-Afghan relations, most recently shaken by last month's burning of copies of the Muslim holy book at a U.S. military base north of Kabul.
Anti-U.S. sentiment flared into deadly riots after the Koran-burning at Bagram airfield came to light. American officials have said the action was a mistake and offered profuse apologies, but some Afghans, including lawmakers and senior clerics, nonetheless called for harsh punishment of those involved.
Sunday's shootings took place outside Kandahar city, in a pair of adjoining villages, Alkozai and Balandi, residents said.
Speaking on condition of anonymity, military officials said it was believed that the assailant had suffered a mental breakdown. But among Afghans, psychiatric disorders are rarely spoken of, and mental illness is not generally considered a mitigating factor in a violent crime.