Officials with Edmonton Fire Rescue said the investigation was underway, after a double decker bus burst into flames over the noon hour Wednesday.
Firefighters were called to McDougall Hill at about 12:45 p.m., after a bus from Strathcona County was reported to be on fire.
The bus was in the northbound lanes – EFR said flames were seen coming from the bottom of the bus.
Firefighters quickly put out the fire, no injuries were reported.
Officials said nine people, including the driver, were on the bus at the time.
CTV News spoke with one of the passengers after the ordeal, Delaina Schweitzer and her mother, along with six kids, were riding the bus when it burst into flames.
“All of a sudden the bus pulled over and then we saw smoke,” Schweitzer said. “Then she said ‘Get out!’
“So we had to run, the smoke was pretty thick and [it was] hard to breathe.”
Schweitzer said the incident was scary, but the bus driver and emergency crews helped to put the group at ease – one fire official stopped to talk with the kids, to make sure they were ok.
The cause of the fire is under investigation – officials said the rear engine compartment on the bus was fully engulfed when crews arrived.
Witnesses reportedly said the bus had been leaking oil all along the Low Level Bridge before reaching the hill.
With files from Danelle Boivin
