Two people who were wanted by police have been killed after a crash on the Forrest Highway at Parkfield, north of Bunbury in Western Australia's South West.

Police attempted to stop the same car on Peel Terrace in Busselton just after 3:00am on Friday morning but it sped off.

Officers searched the area but could not find the vehicle or its occupants — a male driver and a female passenger both in their 20s.

Two police officers at the scene of a crash on the Forrest Highway north of Bunbury where two people died. ( ABC News: Jacqueline Lynch )

A police spokesman said officers had tried to stop the driver for a breath test.

A member of the public spotted the silver sedan crashed into a tree on a median strip on the Forrest Highway around 6:30am, almost 75 kilometres from where police lost sight of it.

Two occupants found dead in the vehicle have been identified, but their names have not yet been disclosed.

A police vehicle parked near the crash scene on the Forrest Highway, north of Bunbury. ( ABC News: Jacqueline Lynch )

The highway was closed to traffic in both directions from Marriott Road to Treasure Road for several hours before being reopened a short time ago.

The Major Crash Unit is investigating the circumstances surrounding the incident, including the failed attempt to stop the car.

Police want to speak to anyone who may have witnessed the crash or have dash-cam vision of the vehicle.