The taxi smashed into a pole, killing the 44 year-old driver and sending the three passengers — all young adults — to hospital, two of them in critical condition.
The accident happened at about 2:30 a.m. PT at the intersection of Gorge Road and Garbally Road.
Victoria Police Sgt. Glenn Vermette said speed is believed to have been a contributing factor, but investigators are looking into what else may have happened.
Taxis in Victoria are required to have internal video cameras running while they operate, Vermette said.
"We'll be downloading that video to see what might have happened inside the vehicle that could have potentially contributed to this crash," says Vermette.
The area is expected to be closed for several hours.