A crash has shut the A4042 in both directions.
Emergency services are at the scene on the dual carriageway near Pontymoile.
Traffic is building up in the area between the Pontypool roundabout and the Rechem roundabout.
A spokeswoman for Wales Ambulance said response vehicles were on their way after receiving a call at 6.20pm.
Gwent Police have advised motorists to avoid the area.
