EDITOR'S NOTE: We are conscious people are sharing this story in the context of the 2020 bushfire crisis. Please be aware the story is from 2018.

Shocking CCTV footage appears to show three teenage girls intentionally lighting a grassfire in Melton West earlier this month.

Investigators are hunting for the brazen trio who lit the fire under the Roslyn Park Drive overpass about 8.50pm on January 3.

The video shows the girls leaning over a concrete barrier into the long, visibly dry grass. They begin to run, but pause briefly and then flee the scene once the grass erupts into flames.