Two lanes on the M4 are closed following a multi-vehicle road traffic collision.
Police closed lanes 1 and 2 on the motorway between junctions 14 (Hungerford) and 15 (Swindon) at around 2.45pm today (28 September).
A number of cars and a horsebox are involved in the incident.
A horse on the hard shoulder appears to be uninjured, according to a passing motorist.
An ambulance and several police vehicles are in attendance.
National Highways are asking motorists to pass with cation whilst emergency services work at the scene.
A Wiltshire Police spokesperson said: “Officers are currently in attendance at a road traffic collision on the westbound carriageway of the M4 close to Membury.
“One of the vehicles involved was towing a horse box, so we are awaiting specialist recovery to assist with moving the horse, which is safe and well.
“Nobody is believed to have been injured.
“Two lanes are currently closed and we are aware of traffic building up, so would ask motorists to avoid the area if possible.”