The crash happened along the 7200 block of Torresdale Avenue just after 10 p.m. on Tuesday.
Police say a red Infiniti was traveling north when the driver swerved into the southbound lanes to avoid hitting a double-parked car.
The vehicle collided with a van that was traveling in the opposite direction.
The 18-year-old driver of the Infinity was taken to the hospital with critical head injuries.
A 23-year-old passenger died after being taken to a nearby hospital.
Authorities say the 42-year-old driver in the van initially ran away from the scene on foot because a crowd started to gather.
"He explained that he felt threatened. That's why, initially, he left the vehicle and left the scene," Chief Inspector Scott Small, with the Philadelphia Police Department, told Action News. "But he did return. He is cooperating with police, and he's very, very lucky because he is not injured."
Another passenger who was in that van was also unharmed, according to police.
Detectives are now reviewing cameras in the area as part of the investigation.