A spokesperson for the U.S. Army's 4th Infantry Division says an Apache helicopter was on patrol Thursday, when it spotted the insurgents, about 20 kilometers northwest of Tikrit. The Apache fired on the men, killing seven and wounding one. Ground forces arrived at the scene a short time later, and discovered three destroyed pick-up trucks, one filled with 50 rockets.

The spokesperson says soldiers also discovered two bunkers nearby, one containing around 300 rockets, and the other several hundred two-meter-long missiles.

The Apache mission was part of Operation Ivy Cyclone, a new U.S. offensive against anti-coalition insurgents in the Tikrit area.

A similar military crackdown, called Operation Iron Hammer began in Baghdad two days ago.

For a second night Thursday, drumbeats of explosions echoed across the capital, as U.S. forces carried out air and ground attacks on suspected insurgent positions.

U.S. military officials say an AC-130 gunship destroyed a former Iraqi Republican Guard building, believed to have been used recently by insurgents to plan attacks against U.S. forces.

In other developments, at least two American soldiers were wounded Friday by a roadside bomb in Baghdad.

In Balad, about 70 kilometers north of Baghdad, gunmen opened fire on a convoy carrying U.S. civilian contractors. One American was killed and another wounded.