Racing at the Tandragee 100 on Saturday was delayed following a major incident in the Junior Support race.
Four competitors crashed at Castle Corner, leaving a scene of destruction.
One rider was airlifted to hospital by the Northern Ireland Air Ambulance, with the other three riders transported to hospital via ambulance. None of the competitors involved are understood to have suffered life-threatening injuries.
The Junior Support race was postponed and the Supersport 600 event was brought forward on the programme.