Three US soldiers were killed by a roadside bomb in Baghdad, and another was killed in combat in Anbar province, the military said Tuesday. The three were killed by a roadside bomb and a secondary explosion near their patrol in southeast Baghdad, the military said in a statement. Another soldier was wounded in the explosions, which took place Monday, the statement said. The unit had been conducting raids against militants in the area, and had recently captured five suspects, it said. Another US soldier was killed the same day while conducting combat operations in Iraq's western Anbar province, another statement said.