Police say it could be the same attacker in all four cases.
Police tell women to be careful in taxis
Earlier today, Montreal police urged women to be careful when using taxis. The SPVM says another woman was attacked downtown over the weekend by her taxi driver.
They recommend people travel in pairs after consuming alcohol, and that passengers ride in the backseat. They also say calling for a cab is safer than hailing one. As well, they recommend taking a photo of the driver's ID, which, by law, should be posted inside the car.
Last month, a CBC investigation revealed that no background checks are done on taxi drivers in Quebec to screen drivers with criminal pasts.
At the time, the government said changing that was a priority.
Police urge people who've been attacked by a taxi driver to report the incident right away to police.