Police are investigating whether speed was a factor in an early morning crash in Werribee that left a woman with life-threatening injuries.
Emergency services were called to Synnot Street just before 2.30 this morning, finding a car had left the road and hit a power pole and tree.
A female passenger in her 20s was critcially injured, while the male driver, also in his 20s, suffered serious injuries.
Police say witnesses described hearing the vehicle coming before the crash.
Synnot Street has been closed between Duncans and Bridge streets.
Anyone with information on the crash, or may have witnessed the collision, are being urged to call Crime Stoppers on 1800 333 000.