Brazilian authorities say they hope to begin retrieving bodies from the wreckage of a Brazilian passenger plane that crashed in the Amazon jungle Friday with 155 people aboard.

Soldiers are clearing the area around the wreckage of the Gol airlines flight to allow rescue helicopters to land.

Authorities say it is unlikely there are any survivors, which would make this the worst air accident in Brazilian history. President Luiz Inacio Lula da Silva has declared three days of mourning.

The Boeing 737-800 went down in the jungle in Mato Grosso state, about 1,700 kilometers northwest of Sao Paulo.

Authorities believe the plane and a business jet may have made mid-air contact leading to the crash. The business jet made an emergency landing and no one was injured.

The Gol flight disappeared from radar after leaving the city of Manaus, bound for the capital city of Brasilia.

Some information for this report was provided by AP and Reuters.