Police, fire and medical services rushed to the scene of a helicopter crash that severely injured its two occupants when it went down near Grand Central airport in Midrand on Sunday afternoon.

The main part of the helicopter's fuselage landed behind a concrete fence while other parts were flung on the road, on the corner of 16th avenue and 2nd road in Midrand.

Emergency workers had to break through the concrete fence to reach the main body while the road was closed in both directions.

"Two men were critically injured in the crash in an abandoned industrial park," said Netcare911 spokesperson Jeffrey Wicks.

"Common cause information suggests that the helicopter crashed and the wreckage disintegrated, the largest segment coming to rest against concrete palisade fencing," he said.

The tail section was found on the other side of the road. The helicopter apparently hit several trees while descending, snapping branches and foliage around the main fuselage where it came to rest.

A man was airlifted by helicopter to the Netcare Sunninghill Hospital while his companion was taken to the same facility by ambulance.

A police helicopter was present at the scene and had since left. The site was being surveyed by emergency officials.

Wicks said the crash would be investigated by the Civil Aviation Authority.