Emergency services are at the scene of an accident involving a light aircraft near Raglan.
Fire crews, two ambulances, a rapid response vehicle and a specialist rescue team were sent to the area at about 11:00am today.
Gwent Police says the incident involved "an accident involving a light aircraft" and was supporting emergency teams at a location in Tregare.
It is not yet clear if there have been any causalities.
The Air Accident Investigation Branch has said it had dispatched a team to the area on Sunday afternoon.
Police have closed the road in both directions between St Peter's Church Bryngywn and Tregare.