A Saskatoon city bus caught fire Friday evening, forcing passengers off the vehicle.

Emergency crews were called to 115th Street, near Dunlop Street in the Forest Grove neighbourhood, around 6:15 p.m.

The bus caught fire somewhere in the engine compartment, which is located near the rear of the bus.

A fire investigator said flames were visible coming from underneath the vehicle. Smoke was pouring outside the bus when crews arrived.

There were signs smoke also made its way inside the bus, the investigator said.

The crew noted a trail of debris and oil behind the bus, the fire department later added in a media release. The fire may have been caused by a mechanical failure.

A replacement bus was dispatched to take the passengers and complete the route. The bus that caught fire — a long, accordion-style bus — was towed back to the transit garage.

No was injured during the incident.

The fire comes as the city tackles a maintenance backlog that has reduced Saskatoon Transit’s total bus fleet and forced the cancellation of several routes.

The city said last week there is a shortage of mechanics to fix and repair busses. Typically, around 100 busses keep transit services running as normal but, as of Friday afternoon, only 79 busses were running.

The city linked the recent service issues to stalled contract talks with the Saskatoon Transit union — or the Amalgamated Transit Union 615.

“Reliable transit service starts with a team of people who are focused on delivering exceptional service and prepared to work together,” the city wrote on its website Friday.

“It is possible that service problems will continue until an agreement with ATU is reached and our work environment has returned to normal.”

Ninety per cent of union members rejected the city’s most recent contract offer in a vote Aug. 15.

The city’s latest offer included a 10 per cent wage increase over four years, retroactive back to January 2013, but a key stumbling block was proposed changes to the defined pension plan. The changes included an increase in contribution rates and changes to how earnings are calculated.

The union said the pension changes are not something they’re prepared to accept.

CTV was unable to confirm Friday when the bus that caught fire was built and when Saskatoon Transit began using it.