State police are investigating what caused a pile-up on I-95 northbound at exit 38 early Saturday morning that sent several people to the hospital.

Just after midnight, four cars collided after another vehicle spun out of control on a wet road, police say. Three people then got out of the vehicle, and were hit by oncoming traffic, according to reports.

In all, nine people were hospitalized with serious injuries, but none are life threatening, police say.

The accident closed the northbound lanes for almost seven hours on Saturday. Police say they continue to investigate and charges are pending.