At least 49 people died Saturday in southern Brazil when a tour bus plunged off a cliff, local officials said.

Authorities warned the death toll at the crash site in Santa Catarina state, in southern Brazil, could rise.

The bus, en route from the neighboring state of Parana, swerved off a curve and fell dozens of meters before crashing in a wooded area. Rescue crews were still trying to rescue survivors and recover the bodies of the victims late Saturday.

Several drivers stopped on the roadside to try to help victims as they waited for emergency services to arrive.

Police did not know how many passengers in all were aboard the bus or whether the driver was one of the victims. Rescue workers said at least six survivors have been pulled from the wooded ravine where the bus landed.

The reason for the crash was not immediately clear.

The bus was about 10 kilometers (6 miles) from its destination in the city of Joinville when it crashed. Highway and weather conditions at the time were good, a police spokesman told Reuters.

Though no immediate cause for the crash had been determined, police told Reuters it appeared the brakes on the bus failed.

Brazil has some of Latin America's deadliest roads. About 43,000 Brazilians are killed in road accidents annually.

Accidents on this winding road are common. The O Estado newspaper said 66 people had been killed on the highway in the last five years, according to a report by the French news agency AFP.

Some material for this report came from Reuters and AFP.