Detective Acting Senior Sergeant Jarrod Dwyer said a red Holden was driving along Hall Road in Carrum Downs about 7.15am on Tuesday when it hit the two workers, who were setting up signage near the intersection of Lats Avenue.
A 44-year-old Bayswater man died at the scene and his 38-year-old workmate from Traralgon is in hospital with life-threatening injuries.
"The driver has just got out, looked directly at the two victims and then run off," Det Act Sen Sgt Dwyer told reporters.
"It is just a callous, cold act. The act of a coward."
He said the man ran and got into a black Hyundai SUV on Rowellyn Avenue a short time after the collision, with witnesses giving chase and taking photos of him and the car.
A short time later police came across the Hyundai, which then drove at officers before again fleeing the scene.
Det Act Sen Sgt Dwyer said the Holden was travelling so fast that it pushed the duo's work ute into a tree on the median strip and threw one of the workers onto the two-lane road.
It is believed the driver may have made an attempt to avoid colliding with the road workers and the ute, but it was too late.
Investigators have made contact with the owner of the car, who is cooperating with police, to determine how the driver got behind the wheel.
They have also released photos of two men, believed to be the drivers of the red Commodore and the black SUV.
"We're pulling out all stops and we will find these people," he said.
"Hand yourselves in ... You will be found."
Anyone who sees the man or the SUV is urged to contact triple zero.
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