US soldier posing next to the corpse of Gul Mudin, an unarmed Afghan civilian killed by their unit on Jan. 15, 2010. A group of rogue US Army soldiers in Afghanistan killed innocent civilians and then posed with their bodies. They also kept their fingers as trophies. (Photo: Der Spiegel)
A US soldier in Afghanistan has killed 10 civilians and wounded five in Kandahar province after suffering a breakdown, officials say.
He left his military base in the early hours of the morning and opened fire after entering local homes, the BBC's Quentin Sommerville reports from Kabul.
Nato said it was investigating the "deeply regrettable incident".
Anti-US sentiment is already high in Afghanistan after US soldiers burnt copies of the Koran last month.
US officials apologised, but the incident sparked a series of protests and attacks that killed at least 30 people and six US troops.
Local people have reportedly gathered near the base in Panjwai district to protest Sunday's killings, and the US embassy is advising against travel to the area.
The soldier, who has not been named, is said to have suffered a nervous breakdown.
He walked off his base at around 03:00 local time (22:30 GMT Saturday).
According to a resident quoted by Associated Press, he opened fire in three separate houses.
After carrying out the killings, he reportedly handed himself over to the US military authorities.
Local tribal leaders said women, children and men were among the dead.
The Nato-led International Security Assistance Force (Isaf) said in a statement that US officials in Afghanistan would work with their Afghan counterparts to investigate what happened.
"This is a deeply regrettable incident and we extend our thoughts and concerns to the families involved," Isaf added.