SAN SALVADOR, JULY 16 -- Six American servicemen, including the deputy commander of the U.S. military group in El Salvador, were killed late last night when their helicopter crashed in stormy weather on the eastern outskirts of the capital, U.S. military and embassy spokesmen said.

Pentagon officials in Washington said Lt. Col. James M. Basile, 43, an Air Force officer from Cheshire, Conn., and deputy commander of the military group, was among the dead. An official said Sgt. Thomas G. Grace, 32, an Air Force medic, was injured in the crash.

Officials did not release the names of the other victims pending notification of relatives.

There was no indication that the crash, which badly damaged the U.S. military UH1H Huey helicopter, was caused by hostile gunfire or sabotage, the spokesmen said. Investigators were working at the site.

"It was strictly weather," said Col. Ron Sconyers, spokesman for the U.S. Southern Command in Panama, the headquarters for all U.S. troops in Central America.

The accident brings to 12 the total of U.S. soldiers who have died in El Salvador during a seven-year-old civil war.

The seven U.S. soldiers left San Salvador's Ilopango military airfield aboard the helicopter last night at 10:40, responding to a call for an emergency medical evacuation team for the eastern province of La Union, Sconyers said.

A U.S. military adviser at the Salvadoran armed forces La Union training school was shot in the neck late yesterday by another U.S. soldier in a "gun-cleaning accident," according to U.S. Embassy spokesman Joseph Macmanus. The adviser, was identified by a Pentagon official as Staff Sgt. Timothy C. Hodge, 29.

As a precaution because of blustery weather, a Salvadoran Air Force helicopter also set out from Ilopango by another route, and arrived safely at La Union.

Hodge, who was evacuated by the Salvadoran helicopter, underwent surgery at a San Salvador hospital for a severed artery in the neck, a Pentagon spokeswoman said. He was reported in stable condition and later flown to an Army medical center in Texas.

But seven minutes after takeoff, the American chopper radioed Ilopango to say it was turning back because of heavy turbulence, Sconyers said. That was its last message.

It crashed just northeast of Lake Ilopango near the village of El Pinal, only a few minutes' flight from its home base, the spokesmen said.

Along with Basile, those on board were three crew members, two Army medical personnel and the commander of the U.S. military trainers stationed at La Union, Macmanus said. The survivor, Grace, was found by Salvadoran civilians. He suffered extensive internal injuries and is being treated in the military hospital in San Salvador.

All the bodies were recovered, and were flown this evening from El Salvador to the Southern Command in Panama, Macmanus said.

It remained unclear how many, if any, of the dead were part of the group of U.S. military trainers, often called advisers, based in El Salvador.

Congress imposed a 55-troop limit on the number of advisers who can be in El Salvador at any time. As of today there were 47 advisers in the country, Sconyers said in a telephone interview. But in recent years the Pentagon substantially increased its personnel in El Salvador by adding what it calls "noncounters," members of the embassy military group and temporary-duty soldiers not directly involved in training Salvadorans.

These include medical teams as well as 18 airmen in three helicopter crews like the one that went down, Macmanus said.

The crews are on two-month tours from Palmerola air base in Honduras. The embassy military group numbers 12, Sconyers said.

Assignments outside the congressional limit have often raised the U.S. military total here to well over 100. The Pentagon said there were 117 here before the copter crash.

In March, Staff Sgt. Gregory Fronius became the first American adviser to die in combat in El Salvador when he was killed in a guerrilla attack on a Salvadoran military base in the north.

In the spring of 1983, guerrillas shot and killed naval Lt. Cmdr. Albert Schaufelberger in his car at a university here, and four Marine embassy guards as they sat at an outdoor cafe.

The U.S. military presence in El Salvador was hotly disputed in Washington during the early years of the war. But as the results of U.S. military training began to show in the more aggressive and less brutal battlefield performance of the Salvadoran Army, the debate subsided. Staff writer Molly Moore in Washington contributed to this article.