Four American soldiers were killed when their vehicle was blasted by a roadside bomb in northern Baghdad, the U.S. military command said Monday.

The deaths took place on Sunday, a military statement said without elaborating. The military had earlier reported the deaths of two other American soldiers on Sunday — one in a roadside bomb explosion in western Baghdad and the other by gunfire in the eastern part of the capital.

On Saturday night, another soldier was killed by a roadside bomb southeast of Baghdad, the military said.

More than 2,600 U.S. military personnel have died since the beginning of the Iraq war in March 2003, according to an Associated Press Count.