Drivers are advised to find alternative routes as there are traffic delays on the M1 following an accident.
One lane is closed on the M1 London bound between J5 A41 at North Western Avenue and the A4008 in Stephenson Way, Watford, as well as J4 A41 at Edgware Way.
Highways England tweeted that one car was involved.
It is not yet known if there any injuries.
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