SAN SALVADOR, El Salvador (AP) _ A group of U.S. Army Green Berets escaped from a luxury hotel in San Salvador this morning after leftist guerrillas abandoned their 28-hour siege of the building and fled.

The soldiers sprinted from a five-story hotel annex when Salvadoran security forces outside assured them the rebels were no longer in the area.

The Green Berets ran crouched, carrying M-16s with grenades on their belts to waiting police pickup trucks that sped off with them.

Reports in El Salvador varied on the number of soldiers had been trapped overnight in the building, but a U.S. official in Washington said there were 12.

President Bush said today that a unit of U.S. Army's elite Delta Force commandos was sent to El Salvador and ''liberated'' the hotel from rebels without a shot. But it appeared the rebels had left the hotel before the U.S. special operations force arrived.

The 12 soldiers inside the hotel, normally stationed with the 7th Special Forces Group in Fort Bragg, N.C., had been in the country at the end of a two- week training mission, said a Bush administration official. They were scheduled to return to the United States Tuesday, when the hotel was beseiged by the rebels, the official said on condition of anonymity.

Most of the from 15 to 20 leftist guerrillas in the hotel apparently slipped away during the night, the Green Berets said.

''We watched them and could have shot them if we wanted to, but that's not our job,'' said one of the Green Berets.

The raid on the hotel by the guerrillas Tuesday was their latest action in an offensive against government troops that began Nov. 11. At least 1,000 people have been killed in the offensive, the biggest in the rebels' decade- old war against a succession of U.S.-backed governments.

The Green Berets had been holed up near a stairwell on the fourth floor of the five-story ''VIP Tower'' while government troops conducted a house-to- house search in the wealthy San Salvador neighborhood of Escalon.

Three bodies were lying in one street, dozens of telephone poles were toppled and thousands of bullet holes were in the hotel. Rifle shots rang out in the area until just 30 minutes before the Green Berets left the hotel.

Reporters who went through the third and fifth floors of the hotel where the rebels were on Tuesday found none this morning. The hotel is known as the El Salvador Sheraton, although it is no longer part of the U.S.-based hotel chain.

Farabundo Marti National Liberation Front guerrillas had seized the hotel annex Tuesday, trapping the Americans, civilian guests and the secretary- general of the Organization of American States, who was on a peace mission. Salvadoran soldiers surrounded the building, and OAS chief Joao Baena Soares and the civilians were evacuated later Tuesday.

Col. Carlos Avilas, a Salvadoran military spokesman, claimed Baena Soares, who returned to Washington late Tuesday, was the target and said two of the diplomat's Salvadoran bodyguards had been killed.

But it was not clear if the rebels had intended to seize the annex.

The group of fighters was not large enough to seize the sprawling hotel complex, and the rebels denied trying to kidnap the OAS chief. One of the trapped U.S. soldiers said the guerrillas appeared surprised and confused when they entered the annex.

The attack on the western neighborhood turned the area into a battle zone and stunned a war-weary city that had just begun to return to a semblance of normality.

The attack provoked a strong reaction from President Bush, who hinted that U.S. military force might be used to assist the trapped Americans. The United States also has said it would expedite military aid to the Salvadorans, and a large U.S. military cargo jet was seen landing at the international airport at 5 p.m. Tuesday.

The men were not part of the group of 55 advisers stationed in El Salvador, a number set by congressional limitation. The congressional stricture allows, however, for the transitional type of training teams that the men were part of, the U.S. official in Washington said.

The United States also has provided $3.5 billion in aid to El Salvador during the 10-year-old guerrilla insurgency, which has claimed the lives of more than 71,000 people, mostly civilians.