At least 15 people were killed and about 30 people injured in a bus accident on Sunday in Paraty near Brazil's second biggest city, Rio de Janeiro, said a source from the local Fire Department.The accident took place around 11.30 a.m. on a coastal road, as the bus, which was transporting about 50 passengers, overturned while travelling between the centre of Paraty, a well-known coastal resort, and nearby Trindade district, Xinhua reported.Trafico Colitur, the company that owns the bus, released a statement, saying that the road is very dangerous and the death toll could rise to 20.The rescue was still underway and the injured were taken to the Hospital São Pedro de Alcântara, in Paraty, for treatment, said the local source.Authorities are investigating the cause of the tragedy and local media are citing a mechanical failure as the cause.