Emergency crews, including police divers and local detectives, remain at the scene of a serious crash in Bunbury.
The accident happened just after 4.30am on Saturday at Bunbury harbour.
A submerged vehicle has been discovered, with recovery of the vehicle under way.
Police are seeking witnesses to the incident.
There have been reports of one man running from the scene of the crash early this morning.
Concerns are held for anyone else who may have been in the vehicle.
Cordons are in place with investigations continuing.
Anyone with information is asked to contact Crime Stoppers on 1800 333 000.
