It happened just before 9 a.m. near milemarker 18.3 in the westbound lanes of I-78 West in Clinton Township.
Authorities say a passenger vehicle rear-ended the tractor-trailer and was crushed underneath the back of the vehicle.
An adult in the front seat was pronounced dead at the scene.
A child was found alive in the backseat with minor injuries.
Westbound lanes are completely closed for the cleanup and investigation, and there is at least a five-mile delay with additional rubbernecking delays on the eastbound side.
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