"It was a powerful explosion, dust and smoke covered the area. At first I couldn't see anything, but then I heard screaming women and children," said policeman Ahmed Hassan, who was at a nearby police station when the bomb went off.

"We rushed with other police to help ... the wounded were scattered all around, and there were body parts on the main street," he said.

Security officials said initial evidence from the blast pointed to a suicide car bomber. They said the bombing appeared to have been carried out by Islamic State of Iraq, al Qaeda's Iraqi wing, which often uses suicide bombers in its attacks.