BAGHDAD, Iraq — A suicide car bomber drove into a gathering of mourners at a funeral for a slain political leader yesterday in northern Iraq, killing 25 people and wounding at least 30, a provincial official said.

The attack came as insurgents pressed their violent campaign against the newly formed Iraqi government for the fourth-straight day, raising the cumulative death toll since Thursday to 116, including 11 U.S. soldiers.

The bomber targeted a funeral ceremony for Sayed Talib Sayed Wahab, an official of the Kurdish Democratic Party in Tall Afar, a town between Mosul and the Syrian border, said Khisru Goran, the deputy governor of Ninevah province.

Goran said that after the explosion, clashes erupted between the insurgents and U.S. and Iraqi forces, which prevented ambulances from picking up the wounded. Customarily, mourners assemble in chairs in the street outside the home of the deceased's family.

"You will never be able to stop these cars," Goran said. "No matter what you do, a person determined to kill themselves, no one can stop them."

The new Cabinet of Prime Minister Ibrahim al-Jaafari is predominantly Shiite Muslim, reflecting the outcome of the landmark elections in January. The Sunni minority, long dominant under deposed President Saddam Hussein, is a minor partner in the government, a fact some analysts fear will fuel an insurgency that is mostly Sunni-driven.

The intensity and coordination of the attacks signals the ferocity of the insurgency's intention to derail any meaningful political and reconstruction progress, one analyst said.

"That's what scares the insurgents more than anything else, that this government is beginning to look like it might be able to rule," Col. Thomas Hammes, an insurgency expert at the National Defense University in Washington, D.C., told The Christian Science Monitor.

In other attacks yesterday, a suicide car bomber rammed a U.S. military vehicle in the Zafaraniyya district of Baghdad, killing four people, including two brothers ages 12 and 15. The boys' older brother said they had been in the area because their father owns a garage near the site of the explosion.

As U.S. soldiers attempted to keep crowds from gathering because of fears of a second blast, witnesses said angry youths shouted at them, "No, you go! The suiciders are after you!"

Several hours later, a car bomb targeted a U.S. military patrol in the Jamiaa neighborhood of western Baghdad, setting at least one military vehicle on fire.

Earlier in the day, six Iraqi policemen were slain during a dawn ambush on their checkpoint in the Nahrwan section of eastern Baghdad, according to an Iraqi police general who would not give his name.

The checkpoint was near a former military college that U.S. forces now use.

A group of about 18 armed men drove up to the checkpoint, which was jointly manned by police and the Iraqi national guard. Some of the attackers also were killed, the general added.

Also in eastern Baghdad, a Sunni Muslim prayer leader, Rahim Ali, was killed in a drive-by shooting. He was the imam of the Nowfal Mosque.

And U.S. military officials said an attempted suicide car bombing at a military base in eastern Baghdad went awry when the red sedan used in the attack caught fire after the bomb failed to detonate properly. U.S. soldiers at the gate saved the driver, who said his family was kidnapped and he was forced to attempt the attack.