A section of the M1 has been closed in both directions due to a serious crash.
Emergency services were called to the northbound carriageway between junctions 20 and 21 in Leicestershire shortly before midday on Tuesday.
National Highways said the southbound side had been closed to allow an air ambulance to land on the motorway, between Lutterworth and the M69 at Leicester.
It said investigation work was expected to continue for some time and advised drivers to avoid the area and allow extra time for journeys.