A car bomb exploded next to an Iraqi police station just outside Baghdad's Green Zone on Saturday, causing an undetermined number of Iraqi casualties and sending a black cloud of smoke into the air. The explosion occurred at about 9:30 a.m. (0630 GMT) near a checkpoint leading to the heavily fortified area, which houses the offices of the interim Iraqi government and several foreign missions, including the U.S. Embassy. Bursts of automatic gunfire were heard following the blast. U.S. Embassy spokesman Bob Callahan said the car bomb detonated close to a checkpoint. He said there were no U.S.-led coalition casualties.