A rider has been airlifted to hospital after a crash in the final lap of the practice session.
The European rider, who was riding a Superstock machine, crashed at Primrose corner, close to the start/finish area of the circuit just four minutes before the session was due to end.
No other bikes were involved.
The rider received lengthy treatment at the scene before being taken by helicopter to hospital in Belfast.
It is not known at this stage if his injuries are life threatening.