U.S. military officials in Iraq say two U.S. soldiers were killed in separate incidents late Wednesday.

One soldier was killed and two others were wounded in an attack on their convoy near the insurgent stronghold of Fallujah. The other soldier was killed, and a civilian interpreter hurt, when their patrol was attacked north of Baghdad.

In other developments, about 240 detainees at Abu Ghraib prison were released Thursday. Aides to radical Shi'ite cleric Moqtada al-Sadr say one of the cleric's senior aides was among those freed.

Meanwhile, a loud explosion was reported from the direction of Baghdad's Green Zone, where Iraqi government offices and the U.S. Embassy are located. The U.S. military had no immediate information on the blast.