Mother And Son Killed In Horror Family Car Crash

A night out to dinner has ended in tragedy for a family of five in regional Victoria.

A 37-year-old woman and her 12-year-old son were killed in the horrific collision with a truck on the Valley Highway at Brimin, which also critically injured the 44-year-old father and two infant boys - aged just eight months and two years.

Victoria Police said the 31-year-old truck driver was travelling on the wrong side of the road when he crashed into the car on Friday night.

Image: Julian Fisher

The family was close to home when the accident happened.

The truck driver, who was treated for shock but received no other injuries, is currently in police custody and it is expected he will be charged over the crash.

On Saturday morning, a motorcyclist believed to be in his 30s, died in a single-vehicle collision along Ironbark Road, Yarrambat.

Police said another motorcyclist was also killed this weekend on Victorian roads.

Image: Seven Network

Police are urging other motorists to take care during the Melbourne Cup long weekend.

"We've had a very poor and tragic start to this long weekend," Command Superintendent John Fitzpatrick told reporters on Saturday.

"The gravity of that scene - to see a family in that position - was very difficult... All of those scenes are terrible to witness.

"What we need to do is we need to be mindful about using the road.

"If you are tired, you need to pull over and have a rest."

Image: Seven Network

Police are now investigating the cause of the truck and car crash.

"Our investigators will be determining whether distraction or fatigue or speed or drugs played a part in this," Fitzpatrick said.

Victoria's road toll now stands at 174 for 2018.