The school van caught fire on Warrington St in Mairehau about 3pm Thursday.
A fire service spokesperson said firefighters from St Albans put out the fire in minutes and no one was injured.
Go Bus operations director Nigel Piper said the fire was most likely caused by an electrical fault. The safety of the rest of the company's large fleet was not a concern.
The company was investigating the fire and working with parents of the students involved.