Philadelphia police say the driver behind the wheel of a speeding silver Cadillac ran down the 5-year-old boy at the intersection of 59th and Cedar Avenue and kept going.
Cynthia Hobbs from West Philadelphia said, "I heard 'boom' and then when I heard 'boom,' I turned my head and said 'oh my God.' I looked back and I saw the little boy laying in the street."
Investigators say Casai West was on his bike around 6:30 p.m. when the car which had the green light struck him.
"It broke my heart, I said I don't believe this [person] left that baby and the baby just rolled," said Madeline Bolden.Bolden and her sister were right behind the vehicle and chased after him.
"He went through the light at Catherine and we went through the light. He kept going and going; he went through stop signs and lights and we were right behind him," added Bolden.They lost him and flagged down an officer.
Meanwhile people rushed to help the little boy who was unconscious in the street.
Hobbs said, "That wasn't even my son and I said how could someone do that to a child, hit a child, and leave that little boy in the middle of the street?"
Police say the suspected hit and run driver was possibly driving a Cadillac de Ville with chrome wheels in the front.
The car would have front end damage now.
Casai's family and neighbors were having an all-day block party on nearby Rodman Street when he was hit, his mother is now by his side at Children's Hospital.
"We are just hoping for the best," Naja Bennett, Casai's aunt, said.