Iraqi officials say a suicide bomber has blown himself up inside a Sunni mosque in Baghdad, killing at least five people. Other reports with additional deaths have not yet been confirmed.

In other violence Sunday, an explosive device attached to a police car in the northern city of Mosul killed a policeman and wounded four others. In Baghdad, two additional bomb attacks wounded at least four people.

And a fifth bomb attack wounded two people in the town of Tuz Khurmatu, some 175 kilometers north of Baghdad.

Violence has decreased in Iraq since its peak in 2006 and 2007, but attacks remain common.

U.S. and Iraqi officials have expressed concern about Iraq's ability to handle security after U.S. forces withdraw at the end of the year.