A top Brazilian aviation official said that GOL's flight 1907 with 155 people aboard crashed late on Friday after a mid-air collision.
"What I can say is that there was a collision," Denise Abreu, director of the National Civil Aviation Agency (ANAC), said at a press conference in Brasilia on Sunday.
Authorities were investigating the possibility that the airliner collided with a smaller executive jet during the flight that originated in the Amazonian city of Manaus and was bound for Brasilia and then on to Rio de Janeiro.
Officials indicated the Boeing 737-800 plummeted nose first in the densely forested area of northern Brazil.
Authorities were trying to establish whether the airliner had collided with a US-registered Legacy executive jet whose pilot made an emergency landing on Friday in Cachimbo, near the area where the crew of flight 1907 last made contact, 85 minutes into its flight.
The Legacy's "black box" flight recorder has been withdrawn and will be analysed by investigators, Abreu said.
The seven American passengers and crew aboard the Embraer-made business jet escaped unharmed after the pilot managed to land the damaged plane, which was heading to the United States.
"No one believes we managed to survive a midair collision," said New York Times reporter Joe Sharkey, who was aboard the Legacy said, according to the US daily.
He said neither of the smaller plane's two pilots "can understand how a 737 could have hit us without them seeing it.