A man has been arrested after a fire at a West Yorkshire riding stables in which a two-year-old girl died.Isobel Dobson died in a van which caught fire during the blaze at Hessle Farm, in Wragby, near Wakefield, on Friday evening.Her stepfather and one-year-old stepsister were injured.West Yorkshire Police said a 37-year-old man from Wakefield had been arrested and the fire was now being treated as suspicious.A joint investigation by West Yorkshire Police and West Yorkshire Fire and Rescue Service is continuing.On Saturday, police and firefighters described how the two girls had become trapped in the van and despite the efforts of her stepfather and mother, two-year-old Isobel could not be saved.The family had been at the farm tending to a horse before the fire broke out in a barn being used to store hay.The fire rapidly spread though three barns and then to the family\'s van which was parked nearby.About 20 horses in the neighbouring stables were led to safety by their owners during Friday evening\'s incident.Witnesses said that at the height of the fire flames had been about 50m (150ft) high.About 100 firefighters were called out to tackle the blaze.