Two young men are fighting for their lives following a fatal collision on Christchurch's Memorial Avenue.

Witnesses who saw the Friday night crash say two vehicles were travelling in opposite directions, when a speeding car crossed the traffic island in the centre at speed.

One person died at the scene, and two men in their early 20s remain in a critical condition in Christchurch Hospital's intensive care unit.

Police investigating the incident are yet to pin blame.

The death has been referred to the coroner.