Rescue workers on Sunday hunted through the wreckage of a Brazilian jetliner that crashed in the Amazon rain forest, likely killing all 155 people on board in what would be Brazil's worst air disaster.

The Boeing 737-800 apparently clipped a smaller executive jet midair Friday, crashing in jungle so dense that crews had to cut down trees Saturday to clear a space for rescue helicopters to land. The smaller plane - carrying Americans - safely landed at a nearby air force base.

Some 80 members of the Brazilian Air Force cleared an area in the dense jungle for a helicopter to land, making it possible for authorities to begin pulling bodies out on Monday, said Ademir Ribeiro, a foreman on the nearby Jarina ranch, the center for rescue operations.

"It's extremely difficult to get there, and they need to open a big area for a helicopter to land," Ribeiro said by telephone from the ranch near Peixoto de Azevedo in the central state of Mato Grosso, some 1,090 miles northwest of Rio de Janeiro.

Milton Zuanazzi, general director of the National Civil Aviation Agency, said he had only the slimmest of hopes that any of the 155 people aboard could have survived.

"The possibility of finding survivors diminishes by the minute. We won't lose hope, but it will be very difficult to find survivors," Zuanazzi said in Brasilia, the nation's capital.

President Luiz Inacio Lula da Silva, who ran for re-election on Sunday, declared three days of official morning.

"Brazil is suffering with this. I believe it is the worst aviation accident ever in our country," Silva said in a statement. "We will ask God that our soldiers can find some survivors."

The list of passengers on the commercial jet was not released, and it wasn't clear if any foreigners were aboard.

The Globo news agency said Sunday that police questioned the seven passengers and crew aboard the executive jet, which had been headed to the United States. The passengers, all Americans, included Joe Sharkey, a journalist for the New York Times.

The seven said they felt a bump and the plane shake when Gol Flight 1907 clipped the smaller jet midair, Globo reported. The pilot then took manual control for the landing, the paper said.

Celio Wilson de Oliveira, the Mato Grosso state Secretary of Justice and Public Safety, said the commercial plane crashed near a reservation of the Kayapo Capoto-Jarina Indians in Xingu Park, and Indians with machetes were reportedly hacking their way toward the crash site. But Ribeiro said rescue workers were keeping everyone away from the wreckage.

If all 155 passengers and crew are dead, Friday's crash would be the worst in Brazilian history. Previously, the deadliest was the 1982 crash of a Boeing 727 operated by the now-defunct Vasp airline in the northeastern city of Fortaleza that killed 137 people.

The flight data recorder of the Legacy was flown to Sao Jose dos Campos, the base of aircraft manufacturer Embraer. The recorders of the 737 had not yet been recovered.

The crash was the first major disaster for Gol Linhas Aereas Intelligentes SA, a Brazilian airline that took to the skies in 2001 with six Boeing 737s, serving seven Brazilian cities. Gol said its jet had been delivered by Boeing Co. just three weeks ago, and had flown only 200 hours.

Photograph 1: Relatives of passengers aboard the Brazilian GOL airliner cry at the Manaus airport, in Amazonas, Brazil, on Saturday. [AFP]

Photograph 2: Relatives of passengers protest at the National Agency of Civil Aviation office, or ANAC , asking for more information of the Gol jet crash at the airport in Brasilia, Brazil, on Sunday, Oct 1, 2006. [AP]