Four people are facing impaired-driving charges after police responded to four separate collisions in the Halifax area Friday evening.

Police say one of the collisions involved a marked police cruiser, which had stopped to help a broken-down motorist. Police say the car was parked with its emergency lights flashing when it was struck from behind by another vehicle.

The officer was able to exit the vehicle and arrested the driver.

The officer was later taken to hospital with non-life-threatening injuries and has since been released.

A 28-year-old man, 29-year-old man, and a 56-year-old man, as well as a 20-year-old woman, are all facing impaired-driving charges in connection with the four collisions.

Police say one man had a blood-alcohol reading more than twice the legal limit, while another man had readings more than three times the legal limit.

Police say the third man was charged with refusal, assaulting a police officer, and was also issued a ticket under the Cannabis Act for allegedly having a quantity of cannabis in his vehicle.