The bombing comes one day after U.S. troops reported that they seized a letter last month asking al-Qaida to help incite civil war between Sunnis and Shiites in an effort to undermine the U.S.-led coalition. Officials said Abu Musab Zarqawi, a Palestinian-Jordanian suspected of al-Qaida links, probably wrote the letter.
The exact death toll from Tuesday's bombing remained unclear, but hospital director Razaq Jabbar told the Associated Press his hospital had received 50 dead and 50 injured from Tuesday's bombing. He added he had heard that three others died at another hospital.
"This figure might increase," he said. "There were some body parts that haven't been identified yet. Some more bodies may be trapped under the rubble."
U.S. officials in Baghdad put the figure at 35 killed and 75 wounded but said those numbers could be higher since Iraqi authorities were handling the investigation. The local Iraqi police commander, Lt. Col. Abdul Rahim Saleh, told the AP the attack was a suicide bombing carried out by a driver who detonated a red pickup as it passed by the station. He also said most of the victims appeared to be Iraqi civilians.
"I am sure it was a vehicle," Saleh said. "We found its engine. It was a suicide operation and a cowardly act."
Lt. Col. Dan Williams, a coalition spokesman in Baghdad, said no U.S. or other coalition forces were hurt.
U.S. paratroopers from the 82nd Airborne Division sealed off the area around the station and refused to allow journalists near the blast site in the predominately Shiite Muslim town of Iskandariya.
Policeman Wissam Abdul-Karim told the AP he was standing in front of a nearby courthouse when "I heard a very strong explosion" and "the blast threw me on the ground."
"It was the day for applying for new recruits," Abdul-Karim explained. "There were tens of them waiting outside the police station."
Iraqi officials say insurgents have killed 300 policemen -- who have been regular targets of suicide bombings. The U.S.-trained force is a pillar of American plans to put Iraqis in charge of security before a scheduled June 30 transfer of sovereignty to a provisional Iraqi government.
In another in a series of attacks on Iraqis who are collaborating with the United States, a suicide bomber blew himself up earlier Tuesday outside the house of Amer Suleiman, who heads the local U.S.-appointed authority in the town of Ramadi. The attack wounded four bodyguards but did not harm Suleiman.