Michigan State Police Trooper Paul Butterfield was shot and killed Monday in Mason County, Michigan, after he pulled over a car for a standard traffic stop.

Butterfield, 43, called in the location and vehicle information to a dispatcher before approaching the car he had pulled over at 6:20 p.m. Monday. Three minutes later, a motorist called police to report that a trooper had been shot in the head.

Butterfield was immediately rushed to Munson hospital and underwent emergency surgery, but died soon after.

Officer.com reports that because Butterfield took the correct steps in reporting the vehicle’s license plate information to dispatcher before his death, they were able to track the prime suspect at a gas station about two hours later. A man and a woman were taken into custody but are still under investigation.

Since the tragedy, Michigan state police have been wearing black “mourning bands” in honor of the fallen officer.

“This senseless incident is a grim reminder that our brave public safety officers put their lives on the line every day when they go to work protecting Michiganders," said Michigan Governor Rick Snyder, Associated Press reports. “They are heroes.”