Police search for second driver after man killed by his own car in Wandin

Police are searching for a second driver after a father was killed by his own car east of Melbourne overnight.

Jason Wong, 39, had been driving home in his white Holden Commodore along the Warburton Highway at Wandin about 10pm when another car began tailgating him, allegedly hitting his rear bumper, according to witnesses.

Police believe Wong and the driver of a green Holden Commodore pulled over, both assessing if there was any damage.

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Detectives said the driver of the green car got back into the vehicle and left the scene.

It is believed Wong stayed outside his car when it rolled back and hit him.

Darren Sadler was driving on the same road when he first noticed a green car allegedly driving erratically and aggressively toward another vehicle, driven by Wong.

"It did look really aggressive and you could hear the green Commodore really revving his car and really pushing it," he said.

When he realised both cars were no longer on the road, he circled back and discovered Wong lying underneath his car.

"We had a gut feeling," he said.

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Emergency services were called to the scene, but the 39-year-old died at the scene.

"We noticed his car was in the gutter. The car was still in reverse, we had to turn off the car. That deteriorated so quick. We couldn't get him out fast enough," Sadler said.

"I (am) not sure how it happened for him to end up underneath.

"We spoke to him the whole time. He knew someone was there with him."

Family and friends gathered along the roadside today adding to a tribute to the much-loved father.

Major Collision Investigation Unit detectives are continuing to investigate and are seeking to identity of the driver of the green vehicle.