A collision at Pine Lodge near the northern Victorian city of Shepparton has left four people dead and another seriously injured.
Police believe a car and ute collided on Pine Lodge North Road, near Cosgrove-Lemnos Road, about 4:45pm.
Four passengers in the car died at the scene while the driver was flown to hospital in a serious condition.
Detective Senior Sergeant Chris Vontunk said all five passengers were believed to be male, but that police were still working to confirm their identities.
"It goes without saying, this collision, we lost four people in a heartbeat. It could have easily been a lot worse," he said.
The driver of the ute, a man aged in his twenties, was not seriously injured and stopped to assist at the scene.
Ambulance Victoria confirmed he was later transported to Goulburn Valley Health Hospital.
Senior Sergeant Vontunk said the exact cause of the collision had not been determined.
"We will explore everything with respect to the environment, the vehicles, distraction, fatigue, impairment, all those sort of things … it's very early on in the investigation," he said.
He said police were looking into whether the driver of the car had "disobeyed" a stop sign.
Senior Sergeant Vontunk said the roads the vehicles were travelling on had speed limits of 100 kilometres per hour.
"We're talking about significant impacts, the scene is quite expansive. Both vehicles ended up in a paddock with a fair bit of debris," he said.
He urged drivers to be cautious and avoid distraction, particularly when travelling on country roads.