The accident happened just before 4:00 p.m. in the southbound lanes in Whitpain Township, about 4 miles north of the mid-county interchange.
All lanes reopened just before 5:00 p.m.
Two people were flown to the Hospital of the University of Pennsylvania. Two others were taken by ground to Abington Memorial Hospital. The injuries are reported serious, but believed to be non-life-threatening.
The accident is under investigation.
