Police are searching for a tipper truck that allegedly reversed into an unmarked patrol vehicle north of Adelaide, before taking off.
The vehicle is alleged to have reversed into a police car at Parafield after it had been stopped on Lawrence Hargrave Way for not displaying a rear number plate.
As the police officer was getting out of the unmarked police vehicle, the driver allegedly rapidly reversed and collided with the front of the car.
A SA Police spokesman said it caused minor damage.
The truck then allegedly sped off past the front of a busy hardware store car park.
The officer was not injured during the incident.
Police believe the truck is a 2007 Mitsubishi Canter tipper truck, and are appealing to members of the public who might recognise it or has information of its location to contact Crime Stoppers on 1800 333 000.