A busy Christchurch road has been blocked following a crash.

A police spokeswoman told chrislynchmedia.com emergency services were called to the single-vehicle crash at the roundabout of Wigram Road and Skyhawk Road.

A witness said the vehicle was on its side and the occupants were trapped.

The roundabout is currently blocked and police are organising traffic management.

Wigram Road has been closed and diversions are in place.