Two U.S. service members killed, six others injured in Afghanistan

Two U.S. service members were killed and six others injured when an individual in an Afghan uniform opened fire on them, the U.S. military said on Saturday.

The incident, which took place in Nangarhar province, occurred after a combined U.S. and Afghan force was returning from a "key-leader engagement," Colonel Sonny Leggett, a spokesman for U.S. forces in Afghanistan, said in a statement.

"We are still collecting information and the cause or motive behind the attack is unknown at this time," Leggett added.