A woman has been killed and several others injured when the minibus taking them to a hen party was involved in a crash with a lorry.
In total 21 women on the bus were injured, seven seriously, after a collision involving a Farmfoods lorry on the M62 near Pontefract, West Yorkshire.
Six air ambulances were called to the scene.
Four were used to take casualties to numerous nearby hospitals.
According to Dr David Macklin from Yorkshire Ambulance Service, crews were faced with "a very difficult scene with multiple seriously injured people", but he praised their "excellent and professional response".
The driver of the lorry, believed to be a local man, has been arrested in connection with the incident and remains in custody, West Yorkshire Police said.
Chief Inspector Mark Bownass, head of the force's roads policing unit, said emergency services were called at around 11.30am to reports of a collision between a large goods vehicle and a minibus from South Elmsall, near Pontefract.
One patient, a woman in her 40s, suffered suspected serious chest injuries and was anaesthetised on scene before being transported, while another was airlifted to hospital also with chest injuries.
Police confirmed an off-duty officer was the first person to report the accident and stayed at the scene to help.
Members of the public also helped give first aid. Dave Walton, assistant chief fire officer at West Yorkshire Fire and Rescue Service, said that firefighters had remarked that the crash was "the worst they had seen in a number of years".
The police have since paid tribute to the efforts of the emergency services and thanked drivers for their patience as they assisted the casualties.
Assistant Chief Constable Craig Guildford of West Yorkshire Police, said: "I want to pay tribute to the efforts that have been made today by colleagues in the emergency services, Highways Agency and Local Authority to what has been a major incident on our motorway network.
"Tragically it has claimed the life of a local woman and our thoughts are with her family as specially trained officer's work to support them.
"I wish to thank them (drivers) for their patience and for bearing with us as we now near the end of recovery work and look to re-open the remaining two lanes of the Westbound carriageway."
Chartered accountant Pritpal Singh (28), from Leeds, was travelling back to his office on the M62 westbound when the accident happened.
He said by 2.30pm everyone going in the same direction as the crash had got out of their cars and started walking around on the road.
"I was about a third of a mile back from where the accident was, I got out and walked up to the scene," he said.
"I could see a minibus which was on its side. It had quite a severe amount of damage on the right hand side.
"The lorry which had collided with it was on the main motorway."
Helicopters were sent by Great North Air Ambulance (GNAA) from near Darlington and Cumbria, while colleagues from North West and Lincolnshire and Nottinghamshire Air Ambulances also attended.
A spokeswoman from frozen food company Farmfoods said that it could not comment at this stage.