The A36 has been shut by police as 999 crews race to a multi-vehicle crash.
Emergency services were called to the road traffic collision on the major route in the area of Chilhampton at around 3.30pm this afternoon (Monday).
Further details are unclear, but National Highways has warned motorists they face delays.
A spokesperson said: “The A36 in Wiltshire is closed in both directions between the A303 (Deptford) and the A30 (Wilton) due to a multi-vehicle collision.
“Wiltshire Police are in attendance and leading the response to the incident.
“Traffic is being diverted via local routes.
“Road users are advised to expect disruption and to allow extra journey time.”