The M1 is closed southbound after a collision believed to be caused by a lorry driver suffering a medical episode.
Emergency services were called to carriageway between J11 for Luton and J9 Redbourn after reports of a lorry in collision with a vehicle, then striking the central reservation.
The driver has been taken to hospital.
A full closure is in place and motorists are asked to avoid the area.
Highways England say 500 litres of diesel has been spilled.
M1 southbound at J10 fully closed and may be for some time. Please avoid area. Whole road may have to be resurfaced.
— BCH Road Policing (@roadpoliceBCH) May 10, 2016
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