The M1 motorway has been shut southbound following a serious multi-vehicle accident, according to National Highways.
An accident near Northampton has led to the carriageway and junctions 15 and 14 at Milton Keynes being shut with traffic stationary.
Emergency services attended and a police investigation was under way, said National Highways.
Traffic diversions were put in place from junction 15 southbound and the road was not expected to reopen until later on Saturday night.
