SAN MATEO (CBS SF) — A Good Samaritan who had stopped to offer assistance to a badly injured victim of a freeway crash on Highway 101 in San Mateo was killed early Friday when he was fatally struck by a second vehicle, authorities said.

California Highway Patrol Officer Kurtis Waldschmid said his agency got a call around 1:54 a.m. reporting the initial crash and then received numerous calls four minutes later reporting that a pedestrian had been struck.

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The initial crash vehicle was blocking the No. 1 southbound lane of Highway 101 near 3rd Street. The Good Samaritan’s vehicle — a BMW — was blocking both the No. 1 and no. 2 lanes with its emergency flashers on.

“A Good Samaritan had stopped (to aid the crash victim) and at some point in time that pedestrian was struck,” Waldschmid told KPIX 5.

The pedestrian suffered fatal injuries. Waldschmid said the driver of the initial crash had suffered major injuries and was transported to a local hospital for treatment.

Witnesses on scene reported seeing the Good Samaritan struck by a blue or green box shaped SUV, possibly a Toyota or Subaru. The vehicle that hit the Good Samaritan fled the collision scene and has not been located at this time.

“It’s a horrible tragedy,” he said. “We appreciate people trying to help out but one of the ways you can help out is insuring your own safety — calling into 911 notifying us so we can get here as soon possible, but not putting yourself in a position of danger … Anytime we have people walking in lanes it’s inherently a dangerous situation.”

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The C.H.P. says the victim was a 31-year-old man from South San Francisco. His name has not been released.

Neighbors expressed outrage that the hit-n-run driver would leave the scene without at least checking on the injured victim.

“I would definitely stop. There’s no way I would just leave someone helpless on the ground. I would definitely stop and see how they are,” says Julie Thompson in the parking lot of Supermarket near the crash.

Investigators say alcohol and drugs do not appear to be a factor for all drivers located on scene. A spokesperson for the C.H.P. says there’s no way the driver would not have known he or she struck someone.

“There’s no chance that the driver who fled would not realize that he hit someone,” said Ofcr. David Morey

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The crash scene remained under investigation. Three northbound lanes of the freeway remained blocked by the investigation and finally was reopened at 6:24 a.m.