There are currently delays of up to 60 minutes.
All lanes on the M1 Northbound within J13 near Milton Keynes closed at around 12pm following a multi-vehicle collision.
Traffic was diverted off the motorway via the exit and entry slip roads.
Emergency services and traffic officers were at the scene.
National Highways reported at 14:00 that the motorway lanes had reopened but there are severe delays of around 60 minutes.
There is currently 6 miles of congestion back to J12.