Sixteen Afghans were killed by a 'rogue' United States soldier who walked off his base and opened fire on them in their homes in the early hours of Sunday morning. The dead include nine children and three women, plus five wounded.
Afghanistan President Hamid Karzai condemned the attack and demanded an explanation from Washington.
The North Atlantic Treaty Organisation's International Security Assistance Force said it had arrested a soldier "in connection to an incident that
The deputy commander of US-led NATO forces, Lt Gen Adrian Bradshaw, expressed "profound regrets and dismay at the actions apparently taken by one coalition member in Kandahar province".
The shooting is likely to worsen relations between Washington and Kabul, which already plunged to an all-time low last month after the burning of Korans at a military base near the Afghan capital.