A major road closure has been put in place after a serious accident involving a car and a lorry on the A449 near Usk.
Emergency services attended the southbound incident between the Raglan and Coldra junctions just before 6am on Thursday.
Crews from Gwent Police, South Wales Fire and Rescue Service and the Welsh Ambulance Service attended, along with assistance from traffic management.
The number of people injured in the crash is currently unknown.
Gwent Police said traffic is being diverted via the A40 which has caused some congestion and delays.
Officers are urging drivers to avoid the area and find alternative routes for their journey.