Isobel Dobson died after being trapped in the vehicle when fire broke out at Hessle Farm, Wragby, near Wakefield, on Friday evening.
Isobel’s mother and 37-year-old stepfather rescued their one-year-old daughter from the van but were beaten back by the flames as they tried to save the second little girl.
Today, West Yorkshire Police said a 37-year-old man, from Wakefield, was being questioned in connection with the fire, which is now being treated as suspicious.
A spokesman said: “A 37-year-old Wakefield man has now been arrested in connection with the incident and is currently in police custody.
“Inquiries into the cause of the fire, which is now being treated as suspicious, are ongoing and a joint investigation is being carried out by West Yorkshire Police and West Yorkshire Fire and Rescue Service.”
Emergency services were called to the fire at about 5.30pm on Friday and found a van and two barns ablaze on their arrival.
Isobel and her half-sister were in the van when the fire broke out.
The 37-year-old man and the girls’ 22-year-old mother rescued the baby from the vehicle but were unable to free Isobel.
The two-year-old’s body was found on Friday night and police confirmed she had died.
A police spokesman said yesterday: “Isobel and her one-year-old half-sister were in the van when the fire broke out and, despite efforts by her 37-year-old stepfather and mother, they were only able to rescue the one-year-old girl before being beaten back by the flames and injured.”
The man and his baby daughter received treatment for burns at Pinderfields Hospital in Wakefield and were discharged yesterday.
The spokesman added: “The family have asked the media to respect their privacy at this very difficult time.”
The family were at the farm tending to a horse at livery stables before the fire broke out.
Yesterday, Assistant Chief Fire Officer Martyn Redfearn, of West Yorkshire Fire and Rescue Service, said: “Our condolences go out to the family and friends of the child.”
He continued: “The firefighters worked very hard and were very moved dealing with this scene, as we always are dealing with tragedies like this.”
Ten fire engines were sent to the scene at the height of the huge blaze and firefighters remained at the farm yesterday.
Police are appealing for any witnesses, or anyone with information that they feel could assist the investigation, to contact the Homicide and Major Inquiry Team via 0845 6060606 or Crimestoppers anonymously on 0800 555 111.