Diversions have been put in place away from a serious accident which has closed the A45 near Northampton.
There is a road closure eastbound between the A428 near Earls Barton and the A509 near Wellingborough following a collision between a van and lorry at 6.15am
There are also reports that the carriageway is closed between Queen Eleanor interchange and Barnes Meadow interchange.
Responding to questions about the length of carriageway closed, Highways England said it was necessary to ensure drivers followed the official diversion route in these circumstances - which is the A428.
Drivers are urged to follow the solid diamond diversion symbol.
The official route is:
Exit A45 at Barnes Meadow and take 4th exit for A428.
Continue through Brafield-on-the-Green until you come to roundabout for A509.
Take first exit onto A509 (London Road). Continue until Turnells Mill roundabout.
Take the second exit then continue under the A45, rejoining the A45 at southern roundabout.