David Furst/Agence France-Presse — Getty Images An Iraqi police officer walked amid the wreckage caused Saturday by a suicide bombing in Baghdad that killed 20 people. The attack at a heavily fortified police compound wounded at least 26 people.

47 Are Killed in Iraq Bombings, 20 in Baghdad

BAGHDAD, March 24 — A suicide bomber driving a truck carrying explosives hidden under construction materials on Saturday was waved through a checkpoint at a heavily fortified police compound in southern Baghdad, where he detonated his payload, killing at least 20 people, an Interior Ministry official said.

The attack was the deadliest of a wave of suicide bombings around Iraq on Saturday that killed at least 47 people, many of them policemen, the authorities said.

Despite the infusion of American and Iraqi troops to Baghdad this year, suicide bombings, a hallmark of the Sunni Arab-led insurgency, have been rising. Maj. Gen. William B. Caldwell IV, the top spokesman for the United States military here, said last week that the number of car bombs in Baghdad reached a record high of 44 in February, of 77 nationwide.

With Shiite militias largely lying low since the start of the security crackdown, American generals say their primary focus is to curtail the Sunni insurgency’s high-profile attacks by raiding car bomb factories and erecting blast walls in areas where large groups of people congregate, like public markets.

The suicide bombing against the police station, in the Dora neighborhood of southern Baghdad, was particularly brazen. The two-story building serves as the district headquarters for a large swath of southern Baghdad. It is set within a perimeter of tall walls, sandbag fortifications, police checkpoints and a chicane of traffic barriers designed to impede a fast approach by a vehicle bomber.

But according to a police official at the Interior Ministry, police officers apparently thought the driver on Saturday was hauling bricks to a site next door, where a new police headquarters is under construction. The driver was waved through and then set off his explosives in a devastating blast that was audible on the other side of the sprawling capital. Those killed were mostly policemen, but several were prisoners being held in the station, the official said. At least 26 people were wounded.

Dora has been one of the most violent areas in the city. A concentrated effort by American and Iraqi troops to seal off and clear the neighborhood last summer did not last, and violence rose sharply. But in recent weeks, American commanders have said that the latest security plan has tamed parts of the district.

Under the plan, thousands of fresh American troops are also being sent to the western province of Anbar, a wellspring and refuge of the Sunni Arab insurgency.

The American military said Saturday that two soldiers were killed in combat on Friday, one in Anbar and the other in Baghdad.

In Suhada, a village in western Anbar near the Syrian border, three suicide car bombers attacked police posts in a seemingly coordinated triple attack. One detonated himself outside a police station, and the other two struck police checkpoints, according to Col. Ahmad Jeedan, an Iraqi Army commander in Qaim. At least eight people were killed and 20 wounded, he said.

Another suicide bomber driving a truck with boxes of new shoes destroyed a Shiite mosque in Haswa, about 40 miles south of Baghdad, killing 11 people and wounding 45, according to an Iraqi Army officer and a police official in Haswa.

At least eight people were killed and another eight wounded in the northwestern town of Tal Afar when a suicide bomber wearing an explosives belt blew himself up inside a food store, the chief of the city’s main hospital said.

In Baghdad, according to an Interior Ministry official, two civilians died in cross-fire between militants and the Iraqi Army in the Sunni neighborhood of Fadhel; a mortar shell exploded in the Kamalia district, killing a woman; gunmen shot and wounded the head of Al Karam Hospital in the Amil neighborhood; a major in the Baghdad police force was assassinated; and 10 unidentified bodies were recovered from the street.

In Baquba, north of Baghdad, two insurgents were killed during clashes with the police, according to a security official in Diyala Province.

Insurgents fired more than 10 mortar shells at a police station in the town of Khan Bani Saad, south of Baquba, killing two civilians, the police said. The authorities recovered four bodies in Swaira, a town north of Kut, in southern Iraq, the police there said. In Wahda, insurgents attacked a hydroelectricity station but were repelled by government security forces stationed there, the police said. Five gunmen were killed.

Qais Mizher contributed reporting from Baghdad, and Iraqi employees of The New York Times from Hilla, Ramada and Tal Afar.