KARACHI, Pakistan - A huge car bomb exploded outside the American Consulate here yesterday, killing at least 11 people and injuring at least 26 in the most vivid demonstration yet of an expanding terror campaign aimed at foreigners and the government of the president, Gen. Pervez Musharraf.

None of those killed were believed to be Americans, but five workers inside the heavily fortified building were slightly injured.

The bomb shook the ground, blew out windows in the nearby Marriott Hotel and sent metal fragments from shattered cars flying for hundreds of yards, leaving a 3-foot crater in the asphalt and a gaping hole in the consulate's thick outer wall.

Police investigators said they suspected the bomb was set off by remote control and that the occupants of the car were themselves victims.

It was the second car-bomb attack in this violent and chaotic city in less than a month. In May, a bomb outside the Sheraton Hotel killed 11 French engineers working on a submarine project for the government and three others in what is believed to have been a suicide attack.

The level of destruction and sophistication in the bombings may point to links between local militant groups and members of al-Qaida who have infiltrated the country after being routed from neighboring Afghanistan.

They share a disgust for Musharraf for bending to American pressure to end support for Islamic militants in Afghanistan and in Kashmir, the disputed Muslim region that has brought India and Pakistan to the brink of war.

News agencies received a statement claiming responsibility for the bombing from a previously unknown group, al-Qanoon, which investigators suspect may simply be a new name for militants who have regrouped after being driven underground in recent government crackdowns.

The attack came one day after a visit to Pakistan by Defense Secretary Donald H. Rumsfeld, who had come as part of a U.S. diplomatic campaign to ease tension over Kashmir and who had expressed concern over the threat of terrorism to Pakistan's government.

'Our nation is at war'

In Washington, the State Department said it would reassess how many Americans to keep in Pakistan. It had already reduced staff in the embassy and consulates, and ordered all dependents to leave, after a grenade attack in March at a church in Islamabad killed five people, including two Americans.

"This is a vivid reminder of the fact that our nation is at war," said White House spokesman Ari Fleischer. "Terrorists will use whatever means are at their disposal, no matter how despicable, to harm Americans and others."

In Houston yesterday afternoon, President Bush called the attack the work of "radical killers" and said: "You know, they claim they're religious people, and they blow up Muslims. They have no regard for individual life."

He then told reporters, with some anger in his voice, "We will continue to hunt them down, and seek justice."

Privately, though, Bush's aides are increasingly concerned that the bombings are a sign that Musharraf's power is eroding, and that both al-Qaida and militants pressing for control over Kashmir are willing to challenge him.

The method of yesterday's bombing was reminiscent of the attacks on American embassies in Africa in August 1998, which killed more than 200 people and were attributed to al-Qaida. Since then embassies and consulates around the world have added fortifications.

The police moved quickly yesterday to identify the vehicles and their occupants at the scene of the attack.

By reconstructing the traffic flow from witnesses and debris, and by tracing license and vehicle identification numbers, they focused on a 1981 Toyota Corolla belonging to a driving school that carried four women, including the school's owner.

The owner and her three passengers had just completed the course and were returning from picking up their licenses, police said.

"We think the bomb was planted in the car," said an officer on the scene, Assistant Superintendent Imran Shaukat. "Someone planned this really, really well."

The car was blasted into fragments, which rained down across a nearby park along with tree branches, license plates, bits of tire tread and dead birds.

Investigators said a second possibility was a white van that was traveling parallel to the car. The young woman and her uncle in the van were distributing wedding invitations.

'They are not human'

The American consul, John Bauman, said an automobile tie rod pierced the roof of his home 300 yards away, on the other side of the park. A second fragment landed on his lawn, almost hitting his gardener.

"We have blood in the driveway," he said.

Altogether, 13 cars and five motorbikes lay bent and shattered. One car was flung across the road and flattened against the side of a gazebo in a park.

The mayor of Karachi, Naimat Ullah, vowed to arrest the people behind yesterday's attack. "The terrorists have no religion," he said.

"They are not Muslim. They are not human. They are just terrorists."