Brazil's air force has located the wreckage of a passenger plane which disappeared over the Amazon rainforest.
Relatives of those on board now fear the worst
The Boeing 737, which had 155 people on board, was flying from Manaus to the capital, Brasilia, when it vanished from radar screens.
It was found in a remote area of the rural state of Mato Grosso.
"It would be very difficult for anyone to survive such a crash," Jose Carlos Pereira, president of the Brazilian airport authority, told journalists.
"Our experience shows that when one cannot find the fuselage relatively intact and when the wreckage is concentrated in a relatively small area, the chances of finding any survivors are practically non-existent," he said.
The plane was operated by budget airline Gol.
"The wreckage of the plane was found 30 kilometres (19 miles) north of the Peixoto Azevedo municipality," the company said in a statement.
Troops are attempting to make their way through the densely forested area to the scene of the crash, armed forces spokesman Maj Adolfo Aleixo told Brazilian television.
Dozens of anxious relatives and friends of those missing gathered at airports in Brasilia, Rio de Janeiro and Manaus during the night, seeking information about their loved ones.
Initial reports said the airliner appeared to have collided with a smaller private plane, but aviation officials now say this cannot be confirmed.
It had been scheduled to fly on to Rio de Janeiro from Brasilia.
Gol has expanded rapidly in recent years to become Brazil's number two carrier.
This is the first major crash involving Gol, which was founded in 2001.
In a statement, Gol said the plane involved was new, having only come into service this month.