The vehicle was traveling from Curitiba to Rio de Janeiro and scheduled to arrive Sunday morning when the accident occurred. The names of the victims, or the number of those injured, were not released by the Federal Highway Patrol.
The injured were taken to four area hospitals.
Relatives awaiting the arrival of the bus complained they received unclear information regarding the accident, the Brazilian newspaper O Globo reported, adding an employee of the bus company eventually read the relatives a list of hospitalized passengers.
One, Cristiane Marcia Upitiz , who awaited her brother's arrival, said, "The [bus] company just announced he is hospitalized, but did not know under what condition."
Another, Juliana de Souza, received a phone call from her brother, aboard the bus, saying he escaped through a window and was not injured.