US troops in Afghanistan have been placed on alert following the killings of 16 Afghan civilians by a US soldier.
US officials warned of reprisals after the soldier went on a rampage in villages near a base in Kandahar. Nine children were among those killed.
Earlier, US President Barack Obama phoned his Afghan counterpart Hamid Karzai to express condolences over the massacre.
US Defense Secretary Leon Panetta has said a full investigation is under way.
The soldier, believed to be a staff sergeant, is reported to have walked off his base at around 03:00 Sunday (22:30 GMT Saturday).
In the villages of Alkozai and Najeeban, about 500m (yds) from the base, he reportedly attacked three homes.
At one house in Najeeban, 11 people were found shot dead, and some of their bodies set alight. At least three of the child victims are reported to have been killed by a single shot to the head.
The US military said reports indicated that the soldier returned to his base after the shootings and turned himself in. Read more at the BBC....