A Vancouver bus driver is under investigation after he fought back against an allegedly abusive commuter, and the ensuing confrontation was caught on tape.

The passenger apparently spat on the driver before trying to board another bus. The driver chased him down.

"Hey! F----head here doesn't ride. He f---ing spit on me," said the driver, who works for the Coast Mountain Bus Company but has not been identified.

"You're not f----ing riding buddy, get off."

The commuter responded: "I never spat on anybody."

The driver then spat on the commuter, before storming back to his own bus and telling others waiting at the station: "Anybody else want to f---ing spit on a bus driver?"

When asked what happened, he told the camera crew: "He didn't pay his fare, he was abusive and threatening and I told him to get off the bus and he spit on me."

While he did break company policy in leaving his bus, a spokesperson for the Coast Mountain Bus Company and a union representative had mixed feelings about the incident.

"Clearly, it's really disturbing to see," the company's Doug McDonald told CTV British Columbia.

But he added that while the company has policies in place so drivers avoid going from "being the victim to turning into the aggressor," it can be "easier said than done sometimes."

Union representative Jim Houlihan said the incident was "disturbing" but he felt sympathetic to the driver.

"You don't know what happened to the driver for the past five or six hours prior to that," he said. "You don't know what happened to the driver the day before, and you don't know how many times they've been spit on before. It's very hard not to react to something that disgusting."

The driver apparently hurt his knee in the incident, which happened Friday afternoon, and was pulled from his shift. Witnesses are being interviewed to confirm whether the commuter spat on the driver first.

Some witnesses told CTV British Columbia that the commuter may be an extremely aggressive panhandler, known to frequent downtown Vancouver.

Last year, a 64-year-old driver was kicked in the face by an angry commuter and required stitches in his eye.

According to the drivers' union, there were 241 assaulted recorded in 2006. In 2005, there were 183 assaults, and in 2004 there were 180.

Brain Bulcic, who has driven a bus for 22 years, said he has never been physically assaulted, but has been verbally abused several times.

"Sure. Calling you names, anything," he said.

With reports from CTV British Columbia