The city's public transit service is investigating what appears to be a driver's expletive-filled rant -- including threats to assault a rider -- that was caught on video and posted to YouTube.

The driver, who isn't shown on camera, can be heard yelling, "If you don't shut your f---ing face, I'm going to stick my fist in it."

The footage, just shy of a minute long, was captured on a cellphone by another passenger who uploaded the clip on YouTube on Thursday.

Alain Mercier, OC Transpo's general manager of transit services, said the transit service is taking the incident seriously.

"Customer relations is always a priority for us and we take this situation very seriously," Mercier said. "... Appropriate action will be taken based on the findings."

According to the YouTube user, the incident took place on bus route 96 as it was heading back to the western suburb of Kanata from the city's downtown core.

"I witnessed quite a few threats by the bus driver before I had a chance to take out the iPhone and get this video," wrote the user. "... it's just me, a mentally ill 20-something male, and the bus driver."

The Youtube user wrote before the driver lay into the man, the passenger was talking loudly on his phone as if it were a microphone and he were a game show host.

This man was saying he "sleeps on the ground, run around with no clothes on, tries to be as spontaneous as possible, that he hates pregnancy and loves nudity," DartPak wrote.

The video clip, with choppy audio, ends with the driver yelling "Shut up! Not a f--ing word, not a sound. When I open that f---ing door, you get out, and you don't say a f---ing word or I'm gonna f---ing kick your f---ing ass."

The young man bolts for the back door and says sorry as he gets off.

A similar incident occurred in February -- also on Route 96 -- when a man who just finished a cigarette boarded the bus.

The driver, caught on video and posted to YouTube, berated the man for smelling like smoke, then unleashed his fury on other passengers.