The city District Attorney's Office says 29-year-old Keith Campbell, of Delaware, could face additional charges in connection with the Wednesday crash.
Witnesses told police Campbell crossed the median into opposing traffic while speeding before crashing into the SUV.
Three people were killed at the scene. A fourth suffered a broken pelvis and other injuries in the crash.
Two of the people killed were members of a string band that had performed in the annual New Year's Day Mummers Parade.
Campbell remains hospitalized in critical condition.
It was not clear if Campbell had a lawyer and attempts to reach relatives have been unsuccessful.