Two people managed to escape from their car after it plunged into the Avon-Heathcote Estuary.

Two people have escaped from a car after it plunged into Christchurch's Avon-Heathcote Estuary.

Emergency services were called to the scene off Humphreys Drive, Ferrymead, about 2.10pm on Wednesday.

Police said two vehicles were believed to have been involved in an incident that caused one group to drive off the road and into the estuary.

JOSEPH JOHNSON/FAIRFAX NZ The pair were treated at the scene by St John.

The car landed upright and the water did not reach above the tyres.

Police said the two occupants were briefly trapped in the car, but escaped with the help of a ladder provided by firefighters.

The pair were treated at the scene by St John paramedics.