Three US troops killed in Afghanistan

A man in an Afghan army uniform shot and killed three American service members this morning in southern Afghanistan, the US military command said.

The shooting happened in Sangin district of Helmand province, said US military spokeswoman Major Lori Hodge. She gave no details and said the military were investigating.

The attack is the third killing this week of coalition soldiers by Afghans they are training to take over responsibility for security once most international forces leave in 2014.