A four-vehicle crash on I-95 involving injuries caused massive traffic backups Sunday afternoon, state police said.

Southbound traffic was diverted off the highway at the Allegheny Avenue exit after four cars collided just north of Center City shortly after noon, police said.

The crash site was between Exit 25-Allegheny/Caster Avenues and Exit 23-Girard/Lehigh Avenues. Southbound traffic through the area remained at a crawl as late as 4 p.m.