The two-car smash about 1.20am on Sunday at the intersection of Hallam and Ormond roads, coupled with fatal collisions in Balwyn and Colbinabbin, took the overnight road toll to six. All were in their teens or early 20s.

Nine people were involved in the Hampton Park smash. An 18-year-old Frankston man from one vehicle was pronounced dead at the scene. Two girls - aged 13 and 15, of Narre Warren South and Hampton Park respectively - died at the scene and a 19-year-old Narre Warren South man died on the way to hospital.

Police were "reassessing how the accident occurred" when the Journal went to print. Based on the damage, they believed speed may have been a factor.

In a macabre scene, the two cars were left crushed with debris spread across Hallam Road. Speaking at the scene, Deputy Commissioner of Road Policing Ken Lay told theJournal: "It's the worst collision we've seen in recent times," he said.

"Unfortunately, four young people have died and two others are fighting for their lives. Most of them are locals and this community will take a long time to get over this."

He said young people needed to take more care when getting behind the wheel.

Hallam Road was closed between the South Gippsland Highway and Ormond Road for most of the morning while police investigated.