The number of casualties from a massive road accident in Brazil on Thursday has risen to 21 dead and 22 others injured, said Brazilian authorities.

The pileup involved two ambulances, a truck and a bus in the southern state of Espirito Santo, near the municipal terminal of Guarapari.

The truck, which was carrying rocks, entered the opposite lane and hit a bus which was travelling between Brazil's largest city, Sao Paulo, and the regional capital of Espirito Santo, Vitoria.

The two ambulances which were travelling behind the bus were unable to avoid it after its collision with the truck.

Thirteen people on the bus were killed and 19 more were injured, while one death and five injuries happened on board one ambulance, three injuries in the other. And the driver of the truck also died.

Another six victims were found without being certain of which vehicle they were travelling on, according to the federal highway police.

Most of the victims were burned to death after a fire broke out after the crashes. Of the 22 people injured, seven were in critical condition at local hospitals.

--BERNAMA