A woman has died, and a child has been airlifted to hospital following a single-vehicle crash in Flynn.

Police say the car was driving along Rosedale Flynns Creek Road at about 7.50pm on Monday when the driver lost control of the vehicle, ran off the road and crashed into trees.

The female passenger died at the scene, and the child was airlifted to hospital with serious injuries.

The male driver of the car was taken to hospital with suspected non-life-threatening injuries and is under police guard.

Major Collision Investigation Unit detectives are investigating the circumstances surrounding the crash.

The passenger is yet to formally be identified.

Anyone who witnessed the collision or with dashcam footage is urged to contact Crime Stoppers on 1800 333 000 or visit www.crimestoppersvic.com.au.