The M1 is shut southbound near Northampton following a ‘multi-vehicle collision during evening rush hour on Monday (May 23)
National Highways says the carriageway is blocked between junction 15A and junction 15.
A spokesman confirmed: “Emergency services are in attendance, more information will follow shortly.”
Sensors show traffic gridlocked back to junction 17 for the M45.
Diversion routes via the A43 and A4500 are expected to be extra busy and drivers bid to get round the congestion.
8.15pm UPDATE: The outside lane is now open between junction 15A and junction 15 but two lanes remain closed.