BAGHDAD (AP) – A suicide truck bomber with explosives hidden under a load of bricks struck a police station in a mainly Sunni area in southern Baghdad on Saturday, killing at least 11 people and wounding 23, police said.

The blast could be heard across the city and sent up a huge plume of black smoke over the skyline.

The attacker detonated his explosives at the concrete blast walls protecting the gate of the Dora police station because he could not go any farther, but the building was heavily damaged, police said.

Those killed included four policemen and seven civilians, including some detainees, while 15 officers and eight civilians were wounded, according to the authorities. Policemen were searching the debris for survivors or more victims, including detainees who were being held in a room inside the station.

The 10:45 a.m. explosion occurred nearly three hours after two mortar shells landed on a Shiite enclave elsewhere in Dora, killing at least three people and wounding seven, police said.

Police Corporal Hussam Ali, who witnessed the blast from a nearby guard post, said the attacker took advantage of construction work being done inside the station and was able to circumvent the tight security to reach the main gate by hiding the explosives under bricks.

He said trucks had been coming in and out all day so the attack vehicle did not raise suspicions.

The blast caused part of the building to collapse and knocked down blast barriers over a car parked near the gate.

“We were very cautious, but this time we were taken by surprise,” Corporal Ali said. “The insurgents are inventing new methods to hurt us.”