The victim is 17-year-old David Silva, who was struck around 10:30 p.m. Tuesday at the intersection of Tyson Avenue and Ditman Street.
"We just heard a terrible thump and I said to my husband 'Oh my God, it must be another terrible accident,'" said witness Lisa Maglio.
Maglio and her husband rushed out their front door and saw Silva bloody and convulsing on Tyson Avenue. His bicycle was lodged underneath a parked vehicle.
"I just brought the towel over and we stayed with him and my neighbor was holding his hands, talking to him, but he wasn't responding," said Maglio.
Investigators don't yet have a make or model of the striking vehicle, only that It's a dark colored car with tinted windows.
Silva lives just a mile from the scene. He remains in critical condition at Aria Health - Frankford.
Anyone with information is asked contact the Philadelphia Police Department at 215-686-TIPS (8477) or at phillypolice.com.