The American solider who is accused of a killing rampage in Afghanistan has been identified as a U.S. army staff sergeant from Washington state.

His name has not been released, but U.S. military officials said he is a married father of two from the Joint Base Lewis-McChord.

Afghan President Hamid Karzai said that 16 Afghan civilians, including nine children, were killed when the American service member left the base and open fired on civilians.

The staff sergeant, who has served up to five tours of duty in Iraq and Afghanistan, is being questioned by U.S. officials in Afghanistan.

They believe he acted alone, but some Afghan parliamentarians are now questioning whether others were involved, claiming it would be impossible for one soldier to cover the ground between the houses that were attacked.

U.S. President Barack Obama conveyed his condolences to Karzai, calling the incident “tragic and shocking.”

Canadian Defence Minister Peter MacKay has denounced the massacre as a “random and cowardly act of violence.”

The rampage took place in a village that has been patrolled by Canadians from 2006 to 2011.