The crash happened overnight in the eastbound lanes of Interstate 78 in Clinton, just past exit 18.
The tractor-trailer lost control before striking the other big rig, which was parked on the side of the road.
The entire highway was shut down for several hours, and two people had to be rushed by helicopter to the hospital.
There is no word on their conditions.
An accident investigation is ongoing, and traffic was backed up for more than 8 miles.
The right lane remains closed.