A baby has been injured when an ambulance skidded on ice and overturned, police said.
The infant was being taken from Preston to Leeds in an ambulance when the vehicle skidded and overturned on the M62 at the junction with the M621, West Yorkshire Police said.
The baby was taken in another ambulance to Leeds General Infirmary (LGI), where the baby was in a "critical but stable condition". The baby boy was four-weeks-old.
Police said there were a number of minor accidents on the stretch of motorway prior to the ambulance overturning at about 8.43am on Sunday.
The female driver of a Toyota Corolla was involved in an accident with a VW Passat and moments later a Nissan Micra crashed into the central barrier. While police were en route to the scene, near Junction 27, the ambulance skidded and overturned at the same location. A spokesman added: "It is believed ice on the roadway was a primary contributory factor."
The ambulance crew were said to be "shocked" by the accident but otherwise unhurt. No-one else was injured, the police spokesman added.
Roads in the region were left treacherous after a heavy frost saw temperatures plunge below freezing.
A spokeswoman for Yorkshire Ambulance Service said the vehicle involved was providing an emergency transfer and was operating its blue lights and sirens at the time of the accident. A doctor and nurse were on board, along with the usual ambulance personnel, the spokeswoman added.
The baby was described as in a "serious condition" prior to the accident but the reason why he was being moved from Preston to Yorkshire has not been disclosed.
The parents of the child were travelling separately.
