The crash occurred between J48 for Minskip and J47 for York shortly after 2am.
The southbound carriageway of the A1(M) is currently closed between junction 48 (Boroughbridge) and junction 47 (Allerton Park) and is expected to be for some time.
The northbound carriageway was also closed for some time but it is now open again according to police.
There is a diversion along the A168 which runs adjacent to the A1(M).