Police say two drivers involved in a fatal crash in the Perth suburb of Bicton were both fleeing a crime scene when one crashed into the other.

It is alleged the men assaulted and robbed a 50-year-old man at Point Walter Reserve last night before fleeing in separate cars.

Police say both men took different routes but 18-year-old, Bradley Ross Taylor, ran a stop sign at an intersection and crashed into his alleged accomplice's car.

The collision killed the 28-year-old driver from Willagee.

An officer in a patrol car reported seeing one of the vehicles, which police say was speeding, so put on the lights and siren, and turned to follow but lost sight of it.

He then came across the crash a short time later.

Resident Stephen Pickford described the crash as horrific.

"Well it sounded like an explosion, it was like a bomb went off." he said.

"The car was t-boned by the other car at this intersection which is notorious."

Mr Pickford says the intersection is so notorious for accidents he set up a security camera outside his home to permanently record the site.

He says the camera captured the crash and the footage has been seized by the police.

"We knew this would happen so we installed a camera," he said.

"It recorded the whole thing but the police have now got it."

He says four paperbark trees at the front of his house probably saved his and his wife's lives.

"We were just here [in the front of the house less than 10 metres from the wreckage of one car] and it saved us from getting killed," he said.

"The car that hit him ended up 50 metres down the street.

"One of the neighbours went to the help of the driver who was hit and held him in his arms."

A neighbour, retired ambulance officer Bob Lockley, says it was too late.

"When I got to the car the policeman there indicated he could not detect any signs of life," he said.

"I checked myself and found the same; couldn't detect any pulse, no sign of any breathing, and no response."

Resident Megan Laird came outside when the smash occurred.

"I heard a really loud bang and then ran outside," she said.

"My neighbour across the road had already come out before me and he'd been chasing the guy down the street.

"He pinned him to the ground."

Investigation

Senior police have denied officers were pursuing the car at the time.

Some residents described hearing a police siren and speeding car moments before the fatal crash.

One told the ABC he could hear the chase for some time prior.

"We were sitting in our back yard and we could just hear the sirens chasing the car," he said.

"At one stage, the sirens seemed to go a bit silent and then all of a sudden you could hear the bang of the incident and then it was just quiet and then you could hear the sirens again."

Another resident Michael McGoldrick says the police car was driving in a controlled manner.

"The police car was driving with lights and a fairly quiet siren on, in a controlled manner, looking for perhaps what was going on," he said.

"But, certainly not in any erratic or high speed style of driving."

The surviving driver, Taylor, has been charged with several offences including dangerous driving causing death, failing to stop, driving an unlicensed vehicle and aggravated assault with intent to rob.

He appeared in the Fremantle Magistrates Court today.