One incident occurred near Target Field, while another took place near the University of Minnesota. Uptown was the scene of another. Three of the four assaults had the victim seated in the front seat of the vehicle.

"The incidents either involved unwanted sexual contact where the driver touched the victim, or the driver attempted to have the victim touch them in some unwanted manner," says Minneapolis police spokesperson Sgt. Catherine Michal. "The victim in each case has either been intoxicated or alcohol was involved."

The assailant in each incident is described as a black male in his 20s to 30s, according to Michal.

Police recommend a handful of precautions to anyone who's using a rideshare service or a taxi.

Make sure a taxi has a city of Minneapolis license displayed. Check to see that the rideshare vehicle's license plate and driver's name match the information on your phone. If you're riding alone, always sit in the back seat.

"At this point we don't know if the suspect is the same person in all of the incidents," Michal says. "We're also in the process of trying to determine if the suspect or suspects actually work for one of these companies or instead is posing to work for them."