Twenty people were killed when a bus and a tanker truck collided and burst into flames.
A further 10 people were injured in the crash on Monday morning in Parana state, southern Brazil.
The truck driver and 18 passengers on the bus burned to death, officials said.
One passenger died of a heart attack shortly after the accident.
Most of the 30 passengers had been on their way to a public hospital for cataract surgeries.
An investigation has been launched into the cause of the accident.