Dozens of trucks and around 100 firefighters have battled a large grassfire at Thornhill Park, between Melton and Wyndham.
The blaze broke out near Rockbank just after 6.30pm on Wednesday.
75 vehicles from CFA brigades around the region were dispatched to the outbreak, which burned across a strip of land 200 metres wide and almost a kilometre in length.
At one stage firefighting aircraft also joined the battle.
Despite the large number of appliances it took crews almost two hours to get the flames under control.
CFA teams remained on site through much of the night, blacking out the last remnants of the fire.
Investigators are expected to be on scene this morning as they try to work out the cause.