Updated

U.S. paratroopers fired on anti-American protesters during a nighttime demonstration, and a hospital reported Tuesday that 13 Iraqis were killed and 75 wounded, including three young boys. Soldiers said armed men had mixed into the crowd and fired at them from nearby buildings.

The deaths outside a school in Fallujah, a conservative Sunni Muslim city and Baath Party (search) stronghold 30 miles west of the capital, highlighted the tense and precarious balance as Americans try to keep the peace in Iraq.

Americans and Iraqis gave sharply differing accounts of Monday night's shooting. U.S. forces insisted they opened fire only upon armed men -- infiltrators among the protest crowd, according to Col. Arnold Bray, commanding officer of the 1st Battalion, 325 Regiment of the 82nd Airborne Division (search), whose troops were involved in the shooting.

"Which school kids carry AK-47s?" Bray asked. "I'm 100 percent certain the persons we shot at were armed."

Protesters insisted their demonstration was unarmed and peaceful.

Dr. Ahmed Ghandim al-Ali, director of Fallujah's general hospital, said the clash killed 13 Iraqis and injured about 75. The dead included three boys ages 8 to 10, he said.

Some residents put the death toll higher, at 15. Survivors said the dead were buried quickly Tuesday morning, in accord with Islamic custom.

No Americans were injured.

The shooting was the third reported fatal clash involving U.S. troops and Iraqi protesters in two weeks, underscoring the problems soldiers face as they try to switch from fighting to peacekeeping.

On April 15 and 16, Marines opened fire during angry demonstrations in the northern city of Mosul. Iraqis said 17 people were killed there, though details remained unclear and the Marines insisted they fired in self-defense.

The shootings, widely reported by Arab news media, have fueled resentment of the U.S. military weeks after the overthrow of Saddam Hussein's regime.

U.S. forces serving in the area said they have been trained in crowd control. About half the company headquartered at the school in Fallujah served in Kosovo peacekeeping operations, 2nd Lt. Devin Woods said.

It was unclear whether the protest that sparked the shootings grew from general animosity toward Americans in Fallujah, a city long considered a stronghold of Saddam support and site of factories suspected of involvement in banned weapons programs.

But it appeared a clash of cultures, at least, was involved.

Residents repeatedly denounced battalion members' use of binoculars and night-vision goggles. They accused soldiers of spying on women from the school's upper floors and rooftop.

Monday's protest started after evening prayers on Saddam's birthday, in the past an occasion for weeklong celebrations. Lt. Col. Eric Nantz said the demonstration involved no more than 200 people -- an indication, Nantz said, of support for American forces.

The Iraqi dead and wounded in hospital wards and homes also included women and children shot inside their walled homes in the neighborhood.

"They shot everyone who moved," said Rafid Mahmoud, standing by the bed of his wounded brother at Fallujah hospital Tuesday. His brother's foot had been amputated.

"Americans are criminals," said 37-year-old Ebtesam Shamsudein, her leg bandaged. Her seven children surrounded her, one boy wearing clothes smeared with bloody palmprints.

U.S. Central Command said paratroopers of the 82nd Airborne Division were fired on by about 25 armed civilians mixed within an estimated crowd of 200 protesters outside a compound troops were occupying.

"The paratroopers, who received fire from elements mixed within the crowd and positioned atop neighboring buildings, returned fire, wounding at least seven of the armed individuals," the Central Command statement said.

A Central Command spokesman, Lt. Mark Kitchens, said coalition forces "have consistently demonstrated their efforts to avoid civilian casualties and practice restraint. Any allegations to the contrary are simply not based on fact."

Air Force Maj. Gen. Gene Renuart, U.S. Central Command's operations director, said the demonstration was apparently in celebration of Saddam's birthday.

Some townspeople, however, said the crowd was objecting to the presence of troops, while others said students wanted the soldiers to leave the school so classes could resume.

Some protesters carried AK-47 assault rifles, Nantz said. U.S. soldiers sent a loudspeaker-equipped truck to urge them to stop firing into the air, he said.

As the chanting crowd milled about, soldiers said, U.S. forces used illumination rounds and a smoke grenade to try to keep gun-toting protesters away.

At one point, Nantz said, soldiers sent out in an armored personnel carrier fired two rounds from a 50-caliber machine gun, also in warning.

A company of the battalion's soldiers, 130 in all, had been based in the school since late last week.

Eventually, soldiers of the company said, protesters closed to within no more than 10 feet of the schoolhouse wall. At that point, U.S. forces said, three men on a nearby roof fired into the school.

"Everybody could see the muzzle flashes," said Sgt. Nkosi Campbell, who commanded the first Americans who fired.

Even then, soldiers exercised restraint, Campbell said. "They turned around and said, "`Hey, sergeant, can we shoot? And that was when they were already under fire."'

Nantz said soldiers fired automatic weapons for 20 to 30 minutes. Because residents carried away the dead and wounded quickly, Bray said troops had no idea about Iraqi casualties overall.

On Tuesday, pools of blood remained outside homes across from the school. Walls of homes were bullet-pitted. No bullet holes from incoming fire were obvious at the school, although soldiers said windows had been shot out.

At the hospital, Arab television stations handed microphones to victims for interviews.

Shamsudein's husband, the man whose foot was amputated, was wounded when he ran to close the gate to keep protesters out and his children in. Shamsuedein was shot trying to help him.

One of her brothers-in-law came out to help. He was shot in the heart and died, relatives and doctors said. The men's mother, 65, stepped outside to see, and was shot in the shoulder.

"They go out to save one another, you know," Mahmoud said. "They are brothers."