A rocket hit a downtown Baghdad park Thursday, killing two civilians even as U.S.-backed forces tried to weaken Shiite extremists and disrupt rocket and mortar strikes from the militia stronghold of Sadr City, according to AP. It was the second rocket to land in a downtown park in three days, apparently after failing to reach the heavily guarded protected Green Zone, which includes the U.S. Embassy and key Iraqi government offices. U.S. forces have stepped up air power and armored patrols in an attempt to cripple Shiite militia influence in Sadr City, a slum of 2.5 million people that serves as the Baghdad base for the Mahdi Army. Seventeen militants were killed in clashes since Wednesday, the military said Thursday. Jalal Eddin al-Sagheer of the United Iraqi Alliance, the largest bloc in parliament which includes Prime Minister Nouri al-Maliki's party, said Thursday that a committee met with representatives of al-Sadr to tell them that his wanted supporters should lay down their arms and surrender and to clear Sadr City of roadside bombs.