A number of people have been injured in a six-vehicle collision, which closed the motorway in Northamptonshire for several hours.
The northbound M1 was closed on Wednesday evening, following the collision, which occurred three-quarters of a mile south of junction 16.
The crash happened at around 4.30pm and a number of ambulances were called to the scene to treat the injured, some of whom are children.
The six vehicles included a lorry and a van, Northamptonshire police said.
One of the casualties has been taken to Birmingham Children's Hospital for treatment, and at least three more to Northampton General Hospital.