The first American journalists allowed by U.S. forces to travel to Grenada from Barbados returned tonight from a guided military tour to report that fierce armed resistance to the invasion forces continued in the southeast of the island.

The journalists, including reporters from The Associated Press and Reuter, confirmed Pentagon reports in Washington that what had yesterday been described as a major remaining stronghold of Cubans and Grenadans on Richmond Hill, inside the capital of St. George's, was now in possession of the Marines.

Although the pool journalists taken to the island today had no details, separate reports today from a group of reporters who had been on the island on their own since Tuesday indicated that resistance from Richmond Hill and elsewhere in the Grenadan capital largely had ceased by early yesterday.

In a news conference yesterday afternoon, Secretary of Defense Caspar W. Weinberger and Chairman of the Joint Chiefs of Staff John W. Vessey Jr. indicated they expected heavy fighting in upcoming efforts to take the hill, where both the Richmond Hill Prison and Fort Frederick, described by U.S. officials as the peacetime base of the Grenadan People's Revolutionary Army, were located.

They noted that the Grenadans were believed to be holding political prisoners on the hill and said they wanted to ensure their safety.

Officials in Washington, who asked not to be identified, said that Richmond Hill finally had been taken Thursday with very little resistance. They said that those who had been defending it, who apparently turned out to be Grenadans, had surrendered or walked away.

"I think (the U.S. forces) pretty much just walked up there," one official said. "The resistance just evaporated."

Officially confirmed U.S. casualties rose to eight dead, eight missing and 39 wounded. Transport planes continued to fly supplies and more paratroopers into the island, located about 70 miles north of Venezuela.

Various reports put Cuban casualties as high as 42 dead. Havana's official news agency, Prensa Latina, put the number of Cuban dead at 18, United Press International reported.

Reporters taken to the island by Marines for a pool report this afternoon said that U.S. artillery and air strikes continued into the hills east of the unfinished airport at Point Salines. They said that hundreds of fresh paratroopers were pouring into the fight, and the airstrip area thundered and crackled with apparently outgoing artillery and machine-gun fire.

According to the AP, a U.S. Army source described the target of the U.S. fire as "a battalion headquarters" of Cuban forces three to five miles east of the airport. Army Lt. Col. Fred Akers said in a briefing on the island, where the reporters apparently were confined to the airport area, that the U.S. forces were strafing Cuban positions in the hills with four or five A7 Corsair jet aircraft.

U.S. officials told the pool contingent of 12 journalists that the U.S. artillery fire was designed to head off a possible counterattack from remaining resistance in southeastern Grenada. AP reported that a military source estimated the U.S. forces controlled about two square miles around the airstrip, where troops landed by parachute during the invasion and pushed outward to gain control.

U.S. military officials who accompanied reporters from Barbados to Grenada this afternoon apparently gave no word of Grenadan casualties or the fate of the political prisoners who were said to be in the Richmond Hill Prison.

Washington Post correspondent Edward Cody, who was on the island from Tuesday morning until yesterday afternoon, said that while artillery and air attacks on the hill had been answered by Grenadan antiaircraft emplacements Tuesday night, the area appeared to be quiet yesterday.

Although Cody left the island in a U.S. helicopter for the USS Guam yesterday afternoon, he returned this morning--again on a U.S. helicopter--to find the area still. Another correspondent, Bernard Diederich of Time magazine, who had arrived with Cody Tuesday and had stayed on the island last night, said he had gone up to the prison himself late yesterday afternoon.

Finding the doors open, Diederich had walked inside and found a small group of prisoners, including Alister Hughes, a Grenadan stringer for The Miami Herald, who had been arrested by the Grenadan military following their overthrow of prime minister Maurice Bishop last week.

Although the prisoners told Diederich they were afraid to walk out, Cody reported, Diederich assured them they were in no danger and exited the prison with them. The journalists said they had no information about the number of Grenadans inside Fort Frederick at that time yesterday, but that the installation was quiet.

Meanwhile, although U.S. intelligence units earlier had believed that Gen. Hudson Austin, head of the military junta that seized power in Grenada two weeks ago, was at the now-fallen Fort Frederick, unconfirmed reports today said that Austin was somewhere in the 133-square-mile island's southern reaches, continuing to resist and holding an unknown number of hostages. The nationality of the reported hostages also was not known.

In Washington, Austin was reported to have asked for safe passage to Cuba or Guyana, according to CBS television tonight. The television network quoted informed sources as saying Austin wanted to go to Cuba. But ABC television said he wanted to go to Guyana.

Fighting was reported at a Grenadan military barracks at Calivigny Point, two miles east of the Point Salines airport, but Pentagon sources said it involved only a few defenders with rifles.

Grenadan Governor General Sir Paul Scoon was expected to make a broadcast to Grenadans tonight. The United States and the six Caribbean nations have asked Scoon, the official representative of Queen Elizabeth in Grenada, to form an interim government pending elections within six months.

Accounts from foreigners leaving Grenada provided the first confirmation that U.S. forces had used carrier-based jet bombers in the operation.

U.S. forces have found "upward of 1,000" Cubans on the island, officials said, about 400 more than the Havana government has said were present. The Cubans were also more heavily armed than expected, officials said. Unconfirmed reports said that as many as 200 Cubans have been flown to Barbados, though Adams denied knowledge of any Cuban prisoners in his country. Spain and Colombia have offered to help transfer home Cubans captured in Grenada.

The International Committee of the Red Cross announced that it had requested permission to enter Grenada to inspect the island's hospitals and living conditions of Cuban prisoners, but a Red Cross spokesman in Geneva said that no response had been received.

The evacuation of American nationals continued.

About 40 Canadian nationals arrived in Barbados aboard a U.S. transport and boarded a jet bound for Canada.

Meanwhile, the United States continued to reinforce its contingent on Grenada.

Several hundred paratroopers of the 82nd Airborne Division boarded transports at Fort Bragg, N.C., for a flight to Grenada.