A multi-vehicle crash has shut down both lanes of the Captain Cook Highway near Oak Beach, according to the Transport and Main Roads Department.

Fire trucks and ambulances have rushed to the scene from Port Douglas, with paramedics reportedly treating four patients including three adults and one child, including two with potentially life-threatening injuries.

The latest TMR update at about 4.10pm states the crash happened between Reynolds Drive and Oak Beach Road.

Delays are expected and drivers making their way to Port Douglas for the Carnivale Macrossan Street Parade are being urged to show patience.