RCMP say it happened early Tuesday in Lloydminster when they answered the call.
Officers identified two pickup trucks they say were connected to the crime, and a spike belt was put down to stop the first vehicle.
RCMP say something happened at the spike belt that caused the officer to shoot his service pistol, but wouldn't give details add no one was hurt.
Two men, a 20-year-old from Lloydminster and a 29-year-old from Onion Lake, Sask., have been arrested.
Police are still searching for a second vehicle which is described as a dark grey 1993 Chevrolet CK2500 with a GMC grill and tailgate with chrome side panels with white tape in a Union Jack design on the back window.
The Alberta Serious Incident Response Team is investigating as well.
"At some point during this incident, shots were fired at the vehicle by an RCMP officer. The pursuit continued until the vehicle stopped. The suspect vehicle contained two men who were both arrested and taken to the local detachment," ASIRT said in a release.
"The ASIRT investigation will focus on the circumstances surrounding the conduct of the officer in firing a service weapon."