The driver of that Lancer has been identified as Michael Dougan, 29, of Philadelphia. Three other victims, also from Philadelphia, were identified as Patrick Chang, 37, Jason Stefaniuk, 33, and William Eder, 23.
Police know that Dougan, Chang and Stefaniuk were wearing their seatbelts, but investigators have been unable to determine if Eder was wearing his.
Investigators said Monday that speed and alcohol are suspected factors in this crash. However, it will be a few more weeks before conclusive test results are in.
Police say the Lancer was travelling speeding southbound between Allegheny and Girard Avenue, making several lane changes. Upon approaching Girard Avenue, the car was in the left lane and made a sudden steering change into the right lane. That's when, police say, the driver lost control.
The car began a clockwise slide, and the left front of the car slid under the left rear of tractor trailer, which was in the right southbound lane of the highway. The car continued to rotate and one of the men was ejected from the car. The vehicle came to a final stop on the southbound exit ramp of Girard Avenue.
RELATED SLIDESHOW: Pictures from the crash scene
The truck driver, 57-year-old Frank Maier, was not injured.
In Port Richmond on Monday, Doughan's family gathered and grieved over their loss. They say the group was heading to a party in Old City when the crash happened.
And, they insist, Dougan was not drinking.
"He wasn't drinking. He was speeding, but he wasn't drinking," said his mother.
The family next door was hurting just as badly. That's where Stefaniuk lived. He and Dugan were best friends. Stefaniuk was an employee of the University of Pennsylvania Museum and spent time in China teaching English.
"They were very, very responsible young adults. This is just a tragedy for us to lose both our sons like this," said Stefaniuk's mother Roseanne.
The accident remains under investigation by state police. Police are asking any witnesses to contact them at 215-560-6199.