A police spokeswoman said: "It appears the driver of a Silver Mitsubishi Carisma suffered a medical episode and crashed over a barrier hitting a police car."
The male driver of the Carimsa was temporarily unconscious and an ambulance was called.
The two police officers in the white Ford Focus police car were uninjured and are directing traffic.
A car has collided head on with a police car on Prince Charles Road in Exeter.
The collision occured at roughly 9am this morning at the Stoke Hill junction just by the Morrisons roundabout.
Vincent Miller, who works for Capital Taxis, witnessed the incident.
He said: “I was parked at the junction on Minginglake Road when I saw a car come straight through the pedestrian crossing, knocking over a lamppost before hitting the police car.
“It seemed to me as if the driver might be unconscious, they were face down. The car wasn’t travelling very fast.”
Emergancy services are still on the scene and the road will be blocked both ways untill vehicles are recovered.