Highways England have warned drivers of long delays on the M1 near Northampton with tailbacks stretching back four miles or more.
At 5pm, Highways England tweeted: "INCIDENT : #M1 Southbound #J18 to #J16 near #Northampton all lanes are currently blocked due to a police incident. We hope to have lane 4 running again soon however there will be some delays for some time. Updates to follow.
"There are long delays on approach to this incident, approx. 4 miles of congestion and building. Please plan ahead of your journey this evening."
The AA was reporting that it was a "rolled over van".
There was no further information relating to the nature of the accident nor any injuries to those involved.