Pedestrians killed in early morning truck collision

Two pedestrians have been hit and killed by a truck near Brookton in Perth’s south-east this morning.

The man and woman in their 20s were walking along Brookton Highway around 12.30am when they were struck.

A local volunteer ambulance crew rushed to the scene but the pair couldn't be saved.

A witness told 9 News she was forced to swerve to avoid two people shortly before the crash.

She says they were standing, huddled under a blanket in the middle of the road.

WA Police Commissioner Chris Dawson said an extensive investigation is underway.

“The loss of two lives on a highway at night is a real tragedy for those families and there's a large investigation underway.” he said.

Major Crash detectives shut down part of the highway for more than six hours to investigate the cause of the crash.

At this stage, no charges have been laid and the truck driver wasn't injured.