The U.S. military said Friday that coalition forces in Iraq killed 18 insurgents in the western city of Ramadi.  VOA's Jim Randle reports from northern Iraq.

A U.S. soldier in Baghdad

Officials say the fighting began late Thursday and continued into Friday.

The U.S. military says insurgents attacked coalition forces with rocket-propelled grenades and machine guns. Coalition forces called in aircraft to hit insurgent positions.

Ramadi is in al-Anbar province, which has been wracked by a Sunni insurgency.

In a separate incident, officials are investigating reports that another U.S. helicopter has crashed about 18 kilometers from Baghdad. It would be the fourth American helicopter to go down in recent weeks.

The top officer in the U.S. military, General Peter Pace, says the large number of helicopter losses is prompting some worry and research at the Pentagon.

General Peter Pace

"Clearly, there has been more effective ground fire against our helicopters in the past couple of weeks," he said.  "I have taken a hard look at that, do not know if this is just what is going to happen statistically when you are flying at that [low] level, and people are shooting at you, or whether there are some kind of new tactics and techniques we need to adjust to."

Meanwhile, Army Col. Bryan Owens, who leads a Brigade of the 82nd Airborne Division, says President Bush's new strategy of sending additional U.S. troops to Iraq and concentrating U.S. and Iraqi combat power in Baghdad may force insurgents to leave Baghdad and head for his area of responsibility north of the capital.

"Because of the pressures in Baghdad, we believe the threat forces will try to move to Salah ad Din and find safe havens," he said.

Col. Owens is setting up more and stronger road checkpoints to intercept these forces.

Meantime, Iraqi officials are holding three days of mourning for victims of suicide bombings in Hillah, 100 kilometers south of Baghdad.

Police said at least 73 people died and another 163 were wounded in Thursday's attacks that struck a crowded market area.

This witness says he saw people flee from the first blast, and some of them ran right into the second explosion.