The collision between the AMR ambulance and a Chevy Impala occurred just before 2:10 a.m. at the intersection of Division Street and Second Avenue North, Billings Police Sgt. Pat Curry said in a news release.
The ambulance had rolled over and two female employees were inside. The women were taken to a hospital with non-life threatening injuries, Curry said.
Two men in their 20s had been in the car. The driver was treated at the scene and taken to jail on suspicion of driving while under the influence. A passenger left the area before police arrived but later called from a hospital to talk to police, Curry said. He reported minor injuries.
Police are investigating.