The M4 in Wiltshire has been closed in both directions.
The motorway has been closed since the early hours.
Croft Road, which crosses the motorway from Old Town, Swindon, to Wroughton is also closed.
INRIX travel monitoring service put out this update at 9.06am: "M4 Eastbound closed, slow traffic due to police incident from J16 A3102 Swindon Road (Swindon West) to J15 A346 Marlborough Road (Swindon East).
"Cameras show that the westbound side has been reopened, however the road remains closed in both directions at J15."
This is an unfolding incident. We will bring you more as we get it in the feed below.