PARIS – The cause of smoke in a SAD 17 bus Wednesday afternoon was a malfunctioning supplementary coolant system that shorted a wire in the engine compartment, transportation director Glenn Sirois said Thursday.

“There was no actual fire,” he said.

Representatives from W.C. Cressey and Son of Kennebunk, which supplies SAD 17 with buses, inspected the Fleetwood model Wednesday and found the problem. The bus, which is covered under a warranty, was towed to the district garage for repairs, Sirois said.

The driver noticed smoke coming from under the hood while driving it on Stock Farm Road off Route 117 and immediately turned it off and called for help, Supt. Mark Eastman said. Firefighters arrived about 2:30 p.m., Assistant Chief William Buffington said. There were no students on board at the time.

Eastman said there was initial concern particularly because it was the same type of bus that exploded into flames in the Oxford Hills Comprehensive High School driveway last fall. The cause of that fire was determined to be an electrical component in the engine