Police officer Edson da Silva says a water truck crashed into a utility pole in Alagoas state, causing the high-tension line to fall on the bus, which had stopped on a narrow dirt road.
He said Friday that five girls and one boy were killed instantly when they touched the line as they left the bus. The victims of Thursday's accident ranged from 13 to 18 years old and included two sisters.
Three students were injured slightly as they scrambled off the bus, while 21 escaped unharmed after local residents turned off the power line's transformer.
The two drivers fled the scene.