Four people were killed and eight others were injured when a passenger van carrying warehouse workers flipped over on the Palisades Interstate Parkway in New Jersey overnight, officials said.

The Ford Econoline E350 was driving through Englewood Cliffs around 1:25 a.m. when it rolled over and landed in the center median near Exit 2, reported ABC Eyewitness News.

The van’s 12 occupants found themselves trapped inside the mangled wreckage and had to be extricated by firefighters.

Four of the passengers were pronounced dead at the scene. The other eight were taken to area hospitals to be treated for injuries ranging from bruises to severe head trauma.

Five of the crash survivors were transported to Hackensack University Medical Center, one to Jersey City Medical Center, one to Holy Name Medical Center in Teaneck and another to Englewood Health.

The van was being used to shuttle employees from a warehouse in upstate New York to their homes at the end of their shift.

ABC Eyewitness News reported that the all victims worked for Amscan, a party supply business in Chester.

Amscan’s parent company is Party City Holdings.

The Daily Voice reported that authorities believe the driver of the van may have fallen asleep at the wheel before the vehicle flipped over.

The victims had not been identified as of Friday, and the cause of the crash is being investigated by multiple agencies.

The southbound lanes of the Palisades Parkway were closed to traffic for hours, blocking access to the George Washington Bridge, but the road has since reopened.