The man who filmed and chased after a car after he heard someone inside yelling for help in Pakenham has spoken out on the terrifying ordeal.

• Scroll down to watch footage of the assault

Witness Chris told Shane McInnes “something just sort of seemed a little bit off”.

Press PLAY to hear his insight and the bravery Chris and his wife showed to help the victim

Detective Sergeant Glen McGowan from Cardinia Crime Investigation Unit has also spoken on the horrifying assault.

“It was really fortunate that those people (Chris) were there,” Sergeant McGowan said on 3AW Mornings.

Press PLAY to hear him comment on the assault

Press PLAY down below to watch the footage of the assault

Image: Supplied