Local media reports say the bus was carrying students to three different Spartanburg schools on Tuesday morning when two pupils in the rear noticed smoke rising outside the bus.
Melissa Robinette, a spokeswoman for a Spartanburg school district, says the driver then parked the bus, helped students evacuate, and then arriving firefighters put out the fire.
Robinette says the 56 students on board were taken to their respective schools by another bus and no one was hurt.
Pictures showed the inside of the bus gutted and part of the front and the roof scorched. Authorities are investigating what caused the fire.