UPDATE: M1 now fully open but delays remain following fatal crash
The collision took place just north of junction 16 at about 3.25am.
The M1 was closed in both directions up until around midday between Junction 16 (Daventry/Northampton) and Junction 18 (Rugby).
Part of the northbound carriageway then reopened, however the southbound remained closed until just before 5pm while police investigations continued.
Highways East Midlands tweeted: “#M1 s/b J18-J16 recovery and carriageway clean-up is now complete. All lanes are now open. Delays remain but should start to ease.”
Long delays remain on the M1 with congestion back to junction 19.
There are also long delays on all major routes around the M1.