Minneapolis police issued an alert Friday warning ride-share drivers, such as those working for Uber and Lyft, that they may be targeted in robbery and carjacking schemes.

More than 40 drivers have been targeted since mid-August, Minneapolis police spokesman Garrett Parten said in an e-mail. Over the past week, there have been more than 12 incidents.

According to the alert sent by the Police Department, the schemes unfold with a ride-sharing request typically made on a stolen phone. When the driver arrives, the prospective rider asks them to wait. Then other vehicles come to block the ride-share driver from leaving.

Parten said armed individuals then force the driver out and demand their cellphones and the code to unlock them, along with their wallets. In some cases, the drivers have been assaulted. The suspects then leave, taking the victims' cars.

Some arrests have been made, according to police.

Ride-share drivers should take extra precautions, especially if asked to wait for a passenger, according to the alert.

Police advise drivers who find themselves in the situation to give up the vehicle, keep calm, and try to remember physical characteristics of the thieves, license plates and details about the vehicles involved. Victims should call 911 immediately, police said, and remain on scene if possible.

Alex Chhith