A Knox Middle School bus caught fire Thursday morning while students were exiting the bus, Rowan-Salisbury School System spokeswoman Rita Foil said.

The fire is believed to have been caused by a malfunction with the transmission, but school officials are awaiting confirmation.

Foil said one student possibly had a minor foot injury while getting off the bus and was looked at by the school nurse. No other students were injured. There were about 40 students on the bus at the time.

Principals and school administrators were to send notification of the incident to parents via the school system’s ConnectED messaging service.

Foil said the bus involved is a 1994 Vista and is a spare that was being used while the regular bus was being serviced.

Transportation Director Tim Beck said he’s proud of the way the bus driver and the students handled the situation because “they knew what to do.”

Bus drivers undergo training for evacuation and students take part, as required by law, in two evacuation drills per year. The drills are conducted in the first 10 days of the first and second semesters of school, Foil said.