Iraqi police say at least four people have been killed and 15 wounded when a bomb exploded on a minibus in Baghdad.

A police officer says Saturday's blast occurred during morning rush hour in an eastern section of the capital.

The officer says those killed and wounded were passengers on the bus. He spoke on condition of anonymity because he was not authorized to talk to the media.

Baghdad continues to be hit by frequent bombings despite a decline in violence over recent months amid a U.S.-Iraqi security crackdown.