SHARJAH, UNITED ARAB EMIRATES, NOV. 3 -- An Indian fisherman aboard a United Arab Emirates boat was killed Sunday evening when a U.S. Navy frigate opened fire on three Arab fishing boats because it thought they might be Iranians, according to port officials and witnesses here.

Fishermen on board the 30-foot open fishing vessel Al-Hudei said tonight that Bikwan Kamgee, 26, of Gujarat, India, died after a machine gun bullet hit him in the head about 7:30 p.m. Sunday as they were returning to this Persian Gulf sheikdom from a day's fishing expedition.

The fishermen's accounts today differed significantly in several details from a Pentagon statement Monday that the guided missile frigate USS Carr had fired warning shots at one of three suspected Iranian speedboats that had appeared to make a high-speed "hostile run" at the U.S. tanker Patriot, which the Carr was escorting.

Rama Madao, 24, another Indian fisherman aboard the Al-Hudei, said in an inteview here tonight that his boat had not been moving toward the convoy ships as the Pentagon said but had been fired on after it had stopped shortly after dark in response to a flashed message from the passing warship, which was escorting a tanker.

{In Washington, a Pentagon spokesman said that "at this point we have no reason to change our original statement" on the shooting. He acknowledged, however, that "we were unable to positively identify the vessels in question as Iranian." But he said that the boat's failure to "heed the appropriate warnings" and the fact that it "continued to proceed toward" the U.S. vessel exhibited "hostile intent," in the view of the American warship, and "gave the indication that it could be Iranian."

{He said that U.S. naval officials in the gulf have been asked to review the incident.}

Earlier today the Iranian Revolutionary News Agency (IRNA), in a broadcast, denied that U.S. forces had fired on any Iranian vessels as claimed and said that the target had been a Sharjah fishing boat and that an Indian sailor had been killed.

"We were coming back from fishing 10 miles off the island of Abu Musa when we were warned to stop by lights flashing from a darkened warship," Madao said tonight. "We signaled that we were stopping with our own lights and reversed engines. But suddenly they fired on us."

The Al-Hudei, like hundreds of other fishing boats in the gulf, does not carry a radio and thus is incapable of hearing or responding to the normal radioed challenges and warnings to shipping from U.S. warships.

Madao said that just before they were fired on he had heard what appeared to be several helicopters hovering in the dark above the fishing boats. The Pentagon statement did not say whether the boats were checked out by helicopters before the Carr opened fire with its .50 caliber machine guns.

The incident seemed to confirm fears here that the increasingly crowded gulf was becoming a dangerous place for navigation, not only for belligerents in the seven-year-old Iran-Iraq war and their allies, but also for the thousands of sailors who make their living shipping and fishing amid a naval buildup that includes an estimated 40 foreign warships and hundreds of Iranian gunboats and armed dhows.

The incident prompted Iran tonight to offer to defend "all merchant ships and tankers, irrespective of their flags, if they are made targets by U.S. forces and if they put out an SOS."

The Iranian promise, made by Kamal Kharazi, the head of Iran's war information headquarters, was seen by some observers here as a deliberate taunt to the United States, which has limited its protection of navigation in the gulf to U.S.-flag ships.

According to IRNA, Kharazi said the U.S. attack Sunday on a "nonmilitary, Shrajah-owned" boat, represented Washington's attempt to "disrupt shipping in the international waters of the gulf in a bid to expand its military presence in the region."

Khazari said he was "warning" the United States that "Moslem combatants will not remain silent toward its provocative acts," implying that Iran might use the fishing boat shooting as an excuse for retaliation.

Kamgee "was hit and fell to the deck," Madao and another Indian crewmen said tonight. The other crewmen were uninjured in the shooting and the boat was not damaged, they said.

Two other similiar Barracuda-type fishing boats were nearby, the fishermen said, waiting for the warship and the tanker it was escorting to pass by.

The Pentagon said Monday that the boats had sped away as soon as they were fired on but Madao said they did not begin to move until the U.S. warship and the tanker had continued on their way.

When the fishing boat reached here, 45 minutes after the shooting, Kamgee was rushed to Qassemi Hospital but was dead on arrival, hospital authorities said.

A harbor official who asked that his name not be used said tonight, "Everyone is now afraid to go out fishing after this incident. They are saying here that if you go out, you will be shot."

The incident was seen as likely to increase concern here at the dangers that have come with the growing U.S. and European naval presence in the gulf since July, when the United States agreed to reflag 11 Kuwaiti tankers and send U.S. warships to protect them.

The frigate Carr took up station in the gulf only last week, shipping officials here said, and its sailors may have been overly jumpy at the appearance of the sort of small fishing vessels that daily -- and nightly -- dot the gulf, fishing or hauling cargoes.

Meanwhile in Kuwait today, a bomb exploded under a police van near the Ministry of Interior, not far from where the commander of U.S. forces in the region was holding talks with Kuwaiti officials.

Kuwaiti sources said Gen. George Crist, who heads the U.S. Central Command, was discussing recent Iranian Silkworm missile attacks on Kuwait.

No one was injured in today's bombing. Crist was reported to have flown from Kuwait later in the day without incident.