Around 30 vehicles were involved in a serious crash on the M40 in Oxfordshire, police said.
The collision happened at about 7.45am, with the motorway currently closed between junction 9 at Bicester and junction 10 at Cherwell Valley services, said Thames Valley Police.
One man was killed in the crash, said police.
The AA said that the road was busy, with schools currently on the half term break and families on weekend trips, reports PA.
Around 30 people were treated for injuries at the scene and that there was fog at the time of the collision, said South Central Ambulance Service,
Police said that the road would be closed for a number of hours, with a number of southbound lanes also closed along the affected stretch, and advised motorists to take other routes.
An ambulance service spokesperson told the Press Association: "It is quite a major collision. We were called at 7.48am to reports of a multiple road traffic collision on the M40, junctions 9 to 10 northbound.
"I understand that there are about 30 vehicles involved. We are currently assessing in excess of 30 patients.
"We have a lot of resources on the scene - ambulances, our helicopter ambulance, rapid response vehicles, our doctor and our hazardous area response team. Fire and police are also at the scene."
The crash occurred one hour after a coach and car crash caused part of the M1 to be closed.