A suicide car bomber detonated his vehicle outside a prison north of Baghdad on Monday, killing 11 people, security sources told the Afghan Khaama Press. At least 15 people were wounded, according to the Iraqi Defense Ministry.

The casualties reportedly include security guards, prison staff and police officers. The BBC said that the attack occurred as many prison employees were on their way to start their shifts at the jail, and may have been part of a prison escape attempt.

Iraqi interior and defense ministries officials said the bomber blew up the car at about 8:00 a.m. at the main entrance of the Hout prison in Taji, about 25 kilometers north of Baghdad.

The attack is the third major attack in about a week in Iraq. Observers said that it "raises questions" about the ability of Iraqi security forces to maintain order after U.S. troops leave in just over a month.

At least 15 people were killed in explosions Saturday at a market in Baghdad and in an area on the city’s western fringe.