The early morning blast ripped into some 300 potential army volunteers waiting for the recruitment center to open. The building, which is surrounded by barbed wire and had sandbagged posts in front of it, is less than a mile from the heavily fortified Green Zone, where the U.S. administration has its headquarters.
U.S. military command told the Associated Press that 47 people were killed and another 55 were wounded.
Col. Ralph Baker of the 1st Armored Division said a man driving a white 1991 Oldsmobile Cutlass Sierra detonated about 300 to 500 pounds of explosives.
"It was a suicide attack by a single male," Baker told Reuters at the scene in the capital. "It was aimed strictly at Iraqis."
"We were standing in line waiting to start our shift in the new army and we saw a white car drive by us and then blow up. Many died. There were about 400 people in line," said Ghassan Samir, one of the wounded taken to Yarmouk hospital.
The attack comes some 24 hours after a car bomb killed up to 53 people when it exploded at a police station south of Baghdad where Iraqis were lined up to apply for jobs.
New evidence emerged this week of a campaign aimed at destabilizing postwar Iraq and undermining U.S. efforts to hand over power to Iraqis in parts of a letter that was intercepted by the U.S. military. The author of the letter is believed to be Musab al-Zarqawi, a Jordanian militant linked to the al-Qaida terrorist network, sentenced in absentia to death in his country for plotting attacks on U.S. and Israeli interests.
The U.S. Army said Wednesday it had doubled to $10 million a bounty for al-Zarqawi who it says is trying to ignite a civil war that would pit Iraq's majority Shiite Muslims against its Sunni Muslim and Kurdish minorities.
"Anybody out there who knows where Zarqawi is, I want to inform you that the reward for Zarqawi was just increased to $10 million," Maj. Gen. Charles Swannack, head of the 82nd Airborne, told a news conference in Baghdad.
Despite the two car bombings, some Iraqi police and army recruits said the attacks would not dissuade them from pursuing the jobs, citing the good pay and a drive to see Iraq released from the U.S.-led occupation.
"If the Iraqis don't join the police and army, that means we are saying to the Americans: 'Stay here forever,'" Haitham Imad, a 29-year-old army recruit who survived Wednesday's blast, told Reuters.
Maan Hatam Mohammed, an officer who works to secure important parts of Iraq's infrastructure, said it was the best way to earn a living in economic conditions where new jobs are difficult to find.
"We're not scared, but we have to be really cautious. We have to be prepared for anything," Mohammed told the news service.
Since Jan. 1, at least 261 Iraqi civilians have been killed in major suicide attacks or car bombings, according to an AP tally based on reports issued by the U.S. military or Iraqi police.