State troopers are investigating a series of collisions in Hunterdon County where a van slammed into a parked police car that was diverting traffic from an earlier crash site.

The first accident occurred around 4:30 a.m. on Sunday on Interstate 78 East in Clinton Township. A tractor-trailer had stopped on the right shoulder when a Ford SUV driven by 41-year-old Brian Zaikowski of Ridgefield Park struck the back of the truck. Zaikowski suffered serious injuries.

Just one hour later, a Ford Transit van carrying seven people crashed into the parked patrol car that was managing traffic following the initial crash.

This second incident resulted in all seven van occupants, including the driver, being hospitalized.

Authorities are working to determine the causes and any contributing factors