BIDDEFORD, Maine — A Maine state trooper in his cruiser at a highway traffic stop was injured when he was rear-ended by another vehicle, causing him to spin around and strike the one he had pulled over, authorities said.

Trooper Patrick Flanagan and the other two drivers suffered non-life-threatening injuries Saturday night, the Maine State Police said in a news release.

Flanagan’s emergency lights were activated on the southbound Maine Turnpike in Biddeford when his cruiser was struck, police said.

Flanagan and the 25-year-old driver of the vehicle that struck his were taken to hospitals. The driver was issued a summons.

The circumstances that led up to the crash are under investigation, police said.

It was the third vehicle crash into a state police cruiser within 48 hours, according to police reports. There were no injuries in the other two.