Three American journalists and one British reporter attempting to cover the invasion of Grenada by U.S. forces were evacuated from that Caribbean island in U.S. helicopters Tuesday afternoon when a local U.S. military commander decided they were in danger, Pentagon officials said yesterday.

Edward Cody, Miami correspondent for The Washington Post; Don Bohning of The Miami Herald; Morris Thompson of Newsday, and British reporter Craig Chamberlain were flown to the USS Guam, a helicopter carrier supporting the U.S. and Caribbean forces on Grenada, where they remained last night, incommunicado and unable to contact their home offices.

Three other newsmen, Time magazine correspondent Bernard Diederich, a New Zealand citizen; Time photographer Claude Urraca, believed to be a French national, and Hugh O'Shaughnessy, correspondent of the Financial Times of London, were still missing and presumed to be in Grenada.

The seven journalists flew from Barbados to Union Island, about 30 miles north of Grenada, on Monday and chartered a fishing boat to take them to Grenada, where they arrived on Tuesday morning, the day of the invasion.

A Pentagon spokesman, Col. Robert O'Brien, said last night in the first official word their offices had received, that the four taken aboard the Guam would be transported to Barbados "when feasible." He offered no explanation as to why their home offices had not been informed that they were in U.S. custody for more than 24 hours after they became, in effect, the first American citizens to be evacuated from Grenada.

O'Brien also said he had no answer to questions concerning why the correspondents had been taken off the island when they encountered U.S. forces, nor why they could not be put in contact with their offices or allowed to file dispatches from aboard the ship.

The Pentagon statement came on a day when American news organizations began to voice increasingly sharp statements about Pentagon management of news from Grenada, and refusal to allow journalists to be on the island.

News about the four came after two days of inquiries from The Washington Post, The Miami Herald and Newsday at the Pentagon, the State Department and the White House. During that period, spokesmen for those agencies imparted various items of information. One report received by The Washington Post from the State Department early yesterday morning--a number of hours after the four apparently were in U.S. government hands--said that, according to a ham radio operator in touch with both State and American medical students on the island, the entire group of journalists were safe and in a hotel in St. George's.

Subsequent reports obtained by The Miami Herald from other ham operators said the journalists were in the custody of the Grenadan military. Reports of heavy fighting in St. George's increased concern among the newspapers that the U.S. units engaged in taking the capital might not know of the journalists' presence, perhaps in enemy custody. A spokesman for the State Department's Grenada task force said at that time that the commander of the overall Grenada operation, as well as his military superiors, had been given a list of the names of the missing journalists and presumably had passed it down the line of command.