The bomb, which blasted a deep crater outside a police station in Baghdad’s biggest slum, wounded more than 40 people. Another casualty was a U.S. soldier with the 4th Infantry Division, who died early Thursday morning from wounds received Monday during a rocket-propelled grenade attack on a convoy northeast of Baghdad. Spain’s Foreign Ministry said the slain officer, José Antonio Bernal Gómez, 34, was an air force sergeant attached to Spain’s National Intelligence Center. A Spanish diplomat in Baghdad told The Associated Press that one of the gunmen who killed Bernal had been disguised as a Shiite Muslim cleric.

In a supposedly well-protected, expensive part of the city, the Spaniard was chased from his home by three assailants and gunned down, barefoot and in his undershorts, a Spanish official said. The Spanish foreign affairs secretary, Ramón Gil-Casares, said that the Iraqi authorities had known that Bernal belonged to Spain’s intelligence body and that he had been gathering information.

“He was a security professional and we don’t know why he opened the door so easily, or if he could have known one of the men in the group or not,” Gil-Casares told reporters in Madrid. The suicide bombing attack and the death of the Spanish officer renewed fears about the vulnerability of so-called soft targets, which have been hit more often since the U.S.-led coalition forces and the civilians working for them tightened their own security.

It was also the latest attack against Iraqis holding official positions, who are often denounced as “collaborators” by people hostile to the American presence here. “I do not want to work anymore for the police,” said Jassim Mihsin, 31, a police officer for 13 years who was only several yards away from the explosion, as he recovered in a hospital bed here. “I am going to find a simple job to avoid problems and explosions.” At the bombing site, mangled police cars were scattered around and debris filled the big courtyard in front of the one-story police building. Scores of American soldiers surrounded the building in Humvees. The attacker drove a white Oldsmobile through the police compound gate, was fired at by officers, then detonated the bomb, Major Majid Abdel-Hameed of the Iraqi police told The Associated Press. An Iraqi policeman who pushed through the huge crowd around the scene was stabbed in the upper right arm after being set upon by spectators. He was treated by military medics. His arrival created a commotion among the crowd, which began chanting, “No, no to America!” A dozen ambulances raced toward the facility after the blast, which occurred about 8:45 a.m. in the sprawling slum of mostly Shiite Muslims known as Sadr City in northeast Baghdad.

The bombing was the latest in a series of assaults that began in early August with an attack on the Jordanian Embassy, followed by car and truck bombings at the UN headquarters in Baghdad and at a Shiite shrine in the southern city of Najaf. More than 120 people were killed in the Najaf attack, including a leading Shiite cleric.

The American soldier, who was not identified, was the 92nd to die by hostile fire since President George W. Bush declared major hostilities in Iraq over on May 1.

Bush, trying to defend the Iraq war in the face of growing doubts at home and mounting U.S. casualties, said Thursday that he had acted to protect Americans from a “madman,” Saddam Hussein, Reuters reported from Manchester, New Hampshire.

“Who could possibly think that the world would be better off with Saddam Hussein still in power?” Bush said during a visit to New Hampshire, site of the first major presidential primary election next year.

“I acted because I was not about to leave the security of the American people in the hands of a madman. I was not about to stand by and wait and trust in the sanity and restraint of Saddam Hussein,” Bush said.