As of 10:00am, Interstate 81 Northbound remains closed Tuesday morning after an early morning crash.The incident occurred around 3:00am in the northbound lanes of Interstate 81 at mile marker 101, just north of the Pine Grove exit.The crash reportedly involved a tractor trailer that rolled off the highway.  There is no word on injuries but a medical was called for at least one victim.  The driver of the truck was reported to be heavily entrapped.Heavy tow crews are at the scene working to recover the truck.