No one was injured when a small Waco Transit bus carrying one passenger caught fire early Wednesday on State Highway 6 near the McLennan County Jail.

Just after 8 a.m. Wednesday, the bus's driver noticed smoke coming from the hood and pulled over to evacuate the bus, said Allen Hunter, assistant general manager of Waco Transit System. Hunter said the bus's engine compartment was fully engulfed in flames within minutes. Assistant Waco Fire Chief Patrick Kerwin said the entire front end and interior of the bus melted.

"Everything was made out of plastic or some toxic material, so that's why it generated a lot of smoke," said Kerwin, noting firefighters saw large clouds of black smoke on their way to the blaze.

Early investigations indicate the blaze was likely sparked by an electrical short, though the cause remained under investigation late Thursday, Hunter said.

The five-year-old bus was on a route from Waco to Marlin that is traveled six times each day through a program called, "Success by Six," Hunter said. The program is part of a partnership between the transit system and Workforce Solutions for the Heart of Texas, and is designed to minimize travel costs for Marlin and Riesel residents who work or go to school in Waco, Hunter said.

Hunter stressed that the transit system holds safety in the "highest regard," which includes eight weeks of training for drivers, and "rigorous," regular vehicle maintenance.

Hunter said as a result of Thursday's fire, the system's entire fleet is undergoing a thorough maintenance inspection.