BAGHDAD, Iraq - A sport-utility vehicle packed with artillery shells blew up today in a crowd of people waiting to volunteer for the Iraqi military, killing at least 35 and wounding 138. Another car bomb north of the capital killed six members of the Iraqi security forces.

The explosion in Baghdad, the deadliest attack since a bombing outside another recruiting center in February, was part of a surge of attacks on U.S. coalition forces and their Iraqi allies ahead of the transfer of sovereignty to Iraqis on June 30.

The blast scattered bodies and debris across a four-lane highway outside Baghdad's Muthanna airport, which is used as a base by both the Iraqi Civil Defense Corps and the U.S. military. The explosion could be heard for several miles and sent a cloud of smoke over the city.

No American or Iraqi troops were injured, U.S. Army Col. Mike Murray said. Most of the victims appeared to be poor Iraqis hoping to join the security forces because job opportunities here are limited.

Another car bomb exploded today in a village near Balad, 50 miles north of Baghdad, killing six members of the Iraqi Civil Defense Corps and wounding four others, the U.S. 1st Infantry Division said. There were no further details.

The ICDC is Iraq's main internal security force, created by the U.S. administrators to battle the country's insurgency.

Many of the victims of the Baghdad blast had just gotten off a bus at about 9 a.m., Murray said. About 100 volunteers were trying to enter the recruiting center when the sport-utility vehicle crashed into the crowd, said Capt. Hani Hussein of the Iraqi Civil Defense Corps.

"We were standing waiting for our turn to register," Rafid Mudhar told The Associated Press from his hospital bed in Karama Hospital. "All of a sudden, we heard big explosion and most of those standing fell on the ground including me."

He said he was unconscious for a while, then managed to reach a nearby ambulance.

Bloody bodies covered in dust were scattered around the blast site. One dead man lay prostrate in the center of a highway median.

Iraqi security forces tried to help the injured as blood-soaked victims were loaded into ambulances and cars. U.S. troops milled around the scene.

At least one artillery shell could be seen lying on the road. Insurgents in Iraq often fashion bombs out of artillery shells and other military ordnance.

Health Ministry official Saad al-Amili said that death and injury tolls were likely to increase.

Surrounded by Western security guards and Iraqi police, interim Prime Minister Iyad Allawi visited the scene and described it as a "cowardly attack."

"We are going to face these escalations," he said. "The Iraqi people are going to prevail and the government of Iraqi is determined to go ahead in confronting the enemies, whether they are here in Iraq or whether they are anywhere else in the world."

Yas Khudair, a member of the Iraqi Civil Defense Corps, said all the victims were "poor people" who "wanted to volunteer to support their families."

British Foreign Secretary Jack Straw said the string of recent attacks would not affect the handover of sovereignty.

"The terrorists used to justify their terror saying it was against the occupation. The occupation is going to end in 12 days time; now the terrorists appear to be trying to stop the transfer of power to the Iraqi people themselves.

"We and the Iraqi people will not be deterred. The transfer of power will take place. Iraqis will take control of their lives."

In other violence, an explosion next to a convoy of water trucks killed one Hungarian soldier and wounded another this morning 40 miles northeast of the Hillah base south of Baghdad, the Hungarian Defense Ministry said. It was Hungary's first military death in Iraq.

British soldiers clashed with Shiite fighters loyal to radical cleric Muqtada al-Sadr in southeastern Iraq today after coalition troops detained one of the militia's leaders, witnesses and the British military said.

No one was hurt, a British military spokesman said.

The trouble began only one day after al-Sadr took steps to honor an agreement meant to end fighting with American forces in the holy cities of Nafaj and Kufa, ordering fighters who did not live in those twin cities to return home.

On Wednesday, a rocket slammed into a U.S. logistics base near Balad, Iraq, killing three U.S. soldiers and wounding 25 other people, including two civilian workers.

An explosion before dawn Wednesday damaged a pipeline carrying crude oil from Iraq's southern fields to the Basra oil terminal in the Persian Gulf. Iraqi engineers had diverted crude shipments to that pipeline after another was bombed two days ago.

"What you are seeing here is effectively a terrorist war against Iraq's critical infrastructure, including the oil infrastructure," coalition spokesman Dan Senor told CNN. "It is an effort to basically, economically, impoverish the Iraqi people."

President Bush, in a speech beamed live to U.S. forces worldwide, said democracy was being born in Iraq despite the killings and pipeline attacks.

"We have come not to conquer, but to liberate people and we will stand with them until their freedom is secure," Bush told several thousand troops at MacDill Air Force Base, Fla., home of the U.S. Central Command.