Two bombs exploded minutes apart near a central Baghdad square on Tuesday, killing at least seven people and wounding 20 as violence increased ahead of a major Shiite holy day later this week. The first Baghdad bomb was in a plastic bag placed near a CD vendor's stand close to the capital's Tahrir Square by a man who fled seconds before the explosion, which killed at least three people, said police Capt. Mohammed Abdul Ghani. Ten minutes later, a second bomb hidden in a drain exploded, killing four more people including one policeman, he said. Officials at two hospitals where the casualties were taken confirmed that seven people were killed and at least 20 wounded in both bombings. The exact motive of the first bomb was unclear. Police Lt. Mohammed Khayoun said the CD vendors may have been targeted because some sold sexually explicit films. The second blast, he added, was aimed at policemen arriving at the scene.