According to the Pennsylvania State Police at Frackville, the crash occured around 3:30pm Monday afternoon, near Milemarker 112.9 in the northbound lanes of 81.
Police say Karl Kramer, 55, of Mahanoy City, was travelling in the passing lane ahead of a box truck driven Robert Dressler, 82 of Lewisburg.
For unknown reasons, Kramer slowed then turned sharply to the right and collided with the front left corner of Dressler's truck.
Both vehicle veered to the right and down an embankment into a group of trees.
Kramer's vehicle reportedly struck a tree violently pinning him in the vehicle where EMS and Fire used the Jaws of Life to free him. Dressler was able to climb out of his vehicle.
Kramer was transported by Schuylkill EMS Ambulance to a Medevac landing zone where he was flown by Medevac 7 to Geisinger in Danville with severe injuries.
Dressler was transported by Schuylkill EMS to Schuylkill Medical Center East with minor injuries.
Assisting at the scene were Minersville Fire & Rescue, Goodwill Hose Company, Yorkville Rescue, and Schuylkill EMS Ambulances.