Military officials said the helicopter was hit by ground fire, after crashing, but that the five soldiers had been safely evacuated.

Witnesses in Tikrit said the helicopter was flying alongside another Black Hawk, when it appeared to be struck by something from the ground, possibly a rocket-propelled grenade.

U.S. Deputy Defense Secretary Paul Wolfowitz, on a tour of Iraq, was in Tikrit north of Baghdad Saturday and visited an Iraq Civil Defense Corps, or ICDC, training facility.

The U.S. military hopes to have 25,000 Iraqis trained for the corps over the next six to eight months. The corps would help battle loyalists of the former Iraqi leader and combatants in Iraq from foreign countries.

Paul Wolfowitz (Defense Dept. file photo)

Mr. Wolfowitz called the ICDC a success story that shows young Iraqis are ready to stand up and fight for their country alongside coalition forces.

Mr. Wolfowitz is on a four-day tour of Iraq, where he is also expected to meet with the Polish commander of a multinational force deployed in Hilla, south of Baghdad.

U.S. forces were attacked Saturday in Baghdad with a roadside bomb. Three soldiers were reported wounded, although none seriously. U.S. military officials at the scene said it may have been a remote-controlled bomb that was placed near an exit ramp. The bomb detonated as a U.S. patrol was passing.

Attacks against coalition forces have been rising over the past several weeks, to as many as 35 a day. U.S. military officials say the increased attacks are the result of the coalition's more aggressive efforts to take the fight to the enemy.

Most of the attacks have occurred to the west of Baghdad in what is called the Sunni triangle. It is an area where there remains strong support for former Iraqi dictator Saddam Hussein.

General Ricardo Sanchez said this week that U.S. forces are seeing coordinated and synchronized attacks at both local and regional levels. He said the attackers are becoming better organized.