A minibus carrying a group of women to a hen night has been involved in a motorway crash with a lorry, leaving one dead and 21 injured.
Firefighters, paramedics and at least six air ambulances were sent to the scene of Friday's collision on the M62 in Pontefract, West Yorkshire.
A number of casualties initially remained trapped in the wreckage of the minibus, but were later freed.
The collision happened on the westbound section of the M62 near Junction 32. Yorkshire Ambulance said 21 people were injured, seven of them seriously.
The driver of the lorry, a local man, was arrested in connection with the incident and remains in custody, West Yorkshire Police said.
Assistant Chief Fire Officer Dave Walton said firefighters had remarked that the crash was one of the worst they had been to.
He said: "The crews that arrived described to me a very difficult scene, some of them saying it was the worst they'd seen in a number of years - and some very experienced fire officers have been attending this scene.
"However, they very quickly got to work and brought in a range of equipment including cutting and lifting equipment to effect as quick a rescue as we could of those casualties who were still in the vehicle."
Speaking at the scene Chief Inspector Mark Bownass, the head of West Yorkshire Police's roads policing unit, said the casualties were taken to numerous local hospitals.
Assistant Chief Constable Craig Guildford, of West Yorkshire Police, added: "Anyone who is concerned about a family member or who has witnessed the collision itself is asked to contact West Yorkshire Police on 101 for information."
A spokeswoman for Yorkshire Ambulance said the alarm was raised at just after 11.30am on Friday.
"Due to the scale of the incident we have enacted our major incident plan and dispatched a number of resources to the scene including ambulances, our hazardous area response team, doctors and air ambulance," the spokesman said.
The injured were taken to hospitals including Pinderfields Hospital in Wakefield and Leeds General Infirmary.
One man who was stuck in traffic on the motorway tweeted: "Nine ambulances, four fire engines and god knows how many police cars have gone past."
Jon Trickett, MP for nearby Hemsworth, tweeted his condolences, saying: "My heart goes out to all in the M62 accident, their friends and family. What should have been a weekend of fun & laughter now a tragedy."