One of the lorries is believed to be a FedEx while the other appears to belong to a company called L M Logistics.
A witness told MailOnline: 'It's horrific. There is what looks like the remains of the back end of the minibus trapped beneath the FedEx trailer, totally wrecked.
'I don't see how anyone could have survived that. There's wreckage along the grass verge and the third lorry is just past the junction.
'It looks like the trailer has become detached as it is at right angles to the cab. There are two big rescues vehicles at the scene using cranes. The road is closed to the previous junction.'
Emergency services are currently still on the scene and the motorway is closed off between Northampton and Milton Keynes.
Motorists are advised to avoid the area while the emergency services work at the scene.
he southbound carriageway between J15 and J14 is currently closed and is likely to remain closed for a significant amount of time
Chief Inspector Henry Parsons from the Joint Operations Unit for Roads Policing, said: 'Emergency services are currently on the scene responding to this collision and road closures are in place.
'We would ask all motorists to please avoid the area, use alternative routes and await further updates before attempting to travel on this route. We appreciate motorists' patience while we deal with this serious incident.
'I would appeal to anyone who witnessed the collision and has not yet spoken to officers to please contact us.
'Anyone who has any information which could assist the investigation should call the 24-hour Thames Valley Police enquiry centre on 101 quoting URN 214 of 26/8.'
Congestion has been building from junction 15a at Northampton Services today as thousands were due to descend on the M1 motorway for the weekend.
Northamponshire Police has asked people coming to the British Moto GP at Silvestone today to allow more time for their journey.
The Highways Agency has advised anyone travelling south to exit at junction 15 and take the A508 southbound through Roade and Grafton Regis to the A508/A5/A422 roundabout at Deanshanger.
They can then exit onto the A5 and continue to the A5/A509 Interchange.