Update 5.30pm: Western Hills Drive has re-opened in both directions.
Update 5pm: Southbound lanes of Western Hills Drive are about to re-open following a three-car crash in the vicinity of the Rust Ave intersection.
The northbound lanes, however, are still blocked, leading to major traffic delays despite police diversions around the crash scene.
Motorists should continue to avoid the area.
The crash is reportedly a head-on. St John medics continue to tend to a number of patients. Their injuries are not believed to be serious.