The new force, known as the Fallujah Protective Army, will be made up of up to 1,100 Iraqi soldiers led by a former general from the military of Saddam Hussein, Lt. Col. Brennan Byrne said.

In violence throughout Iraq, a US soldier was killed in a roadside bombing north of Baghdad, and a foreign civilian was shot to death in an attack on his car in the southern city of Basra. Three members of an Iraqi family were killed when a rocket hit a residential building in the northern city of Beiji.

US troops at the main checkpoint in and out of Fallujah opened fire on a car, killing several Iraqis but there were differing accounts of the circumstances of the attacks.

Marine Capt. James Edge said a car screeched into the razorwire near the main Marine checkpoint into Fallujah and gunmen inside opened fire with assault rifles on the Americans. US troops returned fire with a Humvee-mounted heavy machine gun, killing at least three men in the car, Edge said. A fourth person was wounded but it was not clear if he was in the car or a bystander, Edge said.

An AP reporter, however, saw US soldiers opened fire on a pickup truck at the checkpoint, killing a seven-member family that was trying to flee the city. It was not clear if the accounts referred to separate incidents.

In the south, a US base in the Shia holy city of Najaf came under mortar fire Thursday in an attack that caused no casualties but showed increasing boldness from Shia militiamen in the city. Militiamen also attacked a US convoy passing through part of the city overnight, prompting an exchange that killed an Iraqi woman and wounded six people, hospital officials said.

The Fallujah violence, aired live on television screens with images of explosions and burning buildings, increased pressure on the United States to prevent a revival of the heavy bloodshed in Fallujah during the first two weeks of April.