About 10 blasts were heard in central Baghdad just before 5 p.m., and a huge plume of black smoke rose into the sky as the sun was setting. The U.S. government public address system in the Green Zone also warned people to "duck and cover" and to stay away from windows.
An Iraqi police officer, who spoke on condition of anonymity because he wasn't authorized to release the information, said the blasts were caused by mortars that landed in the Green Zone. U.S. military and embassy officials did not immediately respond to requests for comment.
The heavily fortified area, which houses the U.S. Embassy and thousands of American troops and contractors, along with the Iraqi government's headquarters, has frequently been hit by rockets or mortars. But the attacks have tapered off amid a lull of violence in the capital and surrounding areas.