Arson has been judged as the cause of the fire that killed two promising young apprentice jockeys in an apartment building in Norton, North Yorkshire, England, early Saturday morning. Jan Wilson, 19, and Jamie Kyne, 18, died in the fire, and two other apprentice riders, Ian Brennan and Dean Pratt, were treated at a local hospital and released.\nPolice arrested a man described as in his 30's later the same day, and he was released on bail. A report on the Sporting Life website said that four or five people had returned to the building late Friday night and were having a party when another man who had tried to crash the affair was told to leave after getting into an argument with a man and a woman - not Kyne or Wilson - in the apartment. The fatal fire started a few hours later at about 2:15 a.m.\nWilson was a young woman so devoted to racing that she eschewed any talk of vacation for fear of missing morning workouts. She had recently ridden a winner at Ayr on a horse owned by her parents. Kyne was widely regarded as one of Britain's best young apprentices, having ridden 29 winners this year.