The M1 between Watford and Edgware has been fully reopened following a fatal accident early this morning.
But the motorway is now closed between J6A with the M25 and J6 with the A405 to Bricket Wood due to an incident.
All traffic is being diverted onto the M25.
Two men died and four more were injured in the crash involving two black BMWs near junction five (Watford) at 2.40am.
Police have been carrying out investigation work at the scene all morning and the closure, between junctions five and four (Edgware), has caused gridlock on surrounding road networks.