Witnesses say it was an unprovoked attack.
Transit police spokesperson Ann Drennan says the woman became verbally abusive while trying to board the bus. The driver then decided not to let her on.
"The woman jumped out of the wheelchair and onto the bus and punched the bus operator in the side of the face," said Drennan. "He grabbed her to try to restrain her and she tried to bite him so he let her go."
Surveillance footage taken from a camera at Lime Life Society, a medical cannabis dispensary opposite the scene of the alleged attack, shows a bus lowering a ramp to a woman in a wheelchair.
At the top of the ramp, she stands up from her chair and gets on, but the bus doesn't move.
Minutes later, the woman in the wheelchair comes back to the front of the bus.
Witnesses say that's when she attacked the driver.
Passersby raced to the scene and helped pull her off the bus.
Attacks on drivers becoming frequent
It's the latest in a string of attacks on bus drivers.
Last month, three women were charged after they pulled a female bus driver to the floor by her hair. Just a few weeks ago, a driver had hot coffee thrown at her by a passenger. And in October, a 16-year-old boy punched a bus driver in the face.
It's got so bad, transit police have launched a 'Don't Touch the Driver' campaign to raise awareness and encourage the public to report transit related assaults.
Unifor local 111 vice president Gavin Davies, whose union represents the bus drivers, says it's not enough.
"There needs to be barriers for drivers. We're talking to WCB about this. More needs to be done. This is not cool."
Drennan says the woman initially fled the scene, but was later located at Granville Street Station. She was taken to St. Paul's Hospital. Police say they are contemplating assault charges.