BAGHDAD, April 8 (Xinhua) -- Six U.S. soldiers were killed and four others wounded in insurgent attacks on Sunday, the U.S. military said.

    Three soldiers were killed and another wounded when a roadside bomb hit their patrol in south of Baghdad, the U.S. military said in a statement.

    A fourth soldier was killed and three others wounded by "indirect fire" in separate incident also in south of the capital, another statement said.

    The indirect fire often refers to mortar or rocket attacks in U.S. military statements.

    Two more U.S. soldiers died of wounds sustained during separate combat operations in Diyala and Salahudin provinces in north of Baghdad, the military said in another statement.

    Earlier in the day, the military had announced the killing of four soldiers in roadside bomb attack on Saturday in northeast of Baghdad.

    More than 3,275 U.S. soldiers have been killed in Iraq since the U.S.-led invasion in March 2003, according to media count based on Pentagon figures.