At least 30 people died when a bus plunged off a ridge in southern Brazil on Saturday, authorities said.

Rescue workers were still trying to reach any survivors but access to the crash site in Santa Catarina state was difficult, a local government spokesman told AFP, stressing that the toll could still rise.

The tour bus carrying 50 people plunged 1,300 feet into a wooden ravine as night fell, complicating search efforts, the spokesman said.

The driver is believed to have lost control of the vehicle on the curvy stretch of highway, but the cause was still under investigation.

Still, emergency crews rescued 12 people who survived.

"There are people out there, on the hill, in the bus, trapped in the wreckage. But the chance of finding someone alive are pretty slim," Colonel Nelson Coelho said in a statement.

Some 43,000 Brazilians are killed in car crashes every year.

And from 2002-2012, the traffic accident rate surged by over 24 percent.