Mother and daughter killed in crash on the way home from parent-teacher interviews.

A teenage girl killed in a car crash after leaving parent teacher interviews at her Melbourne school felt “like one of our daughters” to staff, her principal says.

The Year 8 girl and a woman, believed to be her mother, were leaving a Cranbourne East car park on Wednesday night when they were hit by a silver Commodore, police say.

The pair died at the scene.

Lighthouse Christian College principal Jacob Mathews says the student, who had been at the school for one year, was “like one of our daughters”.

“Many of the staff are crying away… she will be sadly missed by all students as well as the teachers,” Mr Mathews told reporters on Thursday.

Crash investigators are examining whether speed or alcohol were factors in the collision.

"We've had some reports that the silver Holden Commodore was seen overtaking a number of vehicles on the South Gippsland Highway prior to the crash," Detective Senior Sergeant Gerard Clanchy told 3AW.

He appealed for anyone who saw the Commodore before the crash to contact police.

The driver, aged in his 20s, was taken to hospital suffering serious injuries.

The deaths are the fifth and sixth on Victoria's roads since Friday, with police urging drivers to slow down and stay safe behind the wheel.

"Too often police are seeing carelessness or recklessness leading to tragedy on the road," acting Assistant Commissioner Tim Hansen said.