Leftist rebels gave a new version Friday of the deaths of three American soldiers whose helicopter they shot down, saying they fired on the aircraft after its crew fired at them.

Meanwhile, a source close to a U.S. Army investigation said a preliminary examination of the bodies showed one of the men had been shot in the head and another suffered multiple bullet wounds, a U.S. Embassy official said.The official, who spoke on condition of anonymity, said it hadn't been determined whether the bullets were fired at close range.

The rebels denied they shot the men execution-style after the crash, as U.S. officials have suggested, and called for an independent autopsy.

"We are so sure that the version is false that we propose the creation of an independent forensic commission to investigate the circumstances in which the North American military men died," said Miguel Saenz, spokesman for the rebel Farabundo Marti National Liberation Front.

To be impartial, Saenz said in a telephone interview, the autopsy commission should not consist of U.S. and Salvadoran government representatives. He did not specify who he thought should be on such a commission.

Some $42.5 million in aid to the Salvadoran military could hang on the determination of how the helicopter crewmen died. That much aid was suspended by Congress last year but President Bush has the authority to restore it under certain conditions.

The U.S. Embassy official said a Salvadoran-crewed helicopter carrying two U.S. Army investigators from the crash site 75 miles east of San Salvador was hit by gunfire Friday during a battle between rebels and Salvadoran troops. The investigator said no one aboard the craft was hurt.

Rebels shot down the helicopter Wednesday. The State Department claimed its early reports indicated two of the men survived the crash and were slain by the rebels.

A rebel communique Friday said guerrillas shot at the helicopter after its crew opened fire on a meeting they were holding with civilians in a combat zone.

That version differed from a communique Thursday that made no mention of any gunfire emanating from the aircraft.

In Washington, a Pentagon spokesman denied the men fired on the village. The helicopter contained a M-60 machine gun and the crew members had personal weapons.