Updated at 4.39pm: A 12 year old boy was seriously ill in the Prince Of Wales Hospital in Shatin Monday after suffering 30 per cent burns to his face, head and chest in a wax-burning accident. The schoolboy was watching other children playing with burning wax in a playground at Wan Tau Tong Estate, Tai Po, when the accident happened on Sunday night. One of the children poured water onto the wax causing an explosive blaze which burnt 30 per cent of the boy's skin on his face, head and chest. Three other boys, aged nine, ten and 12, were also injured from burning wax during the Mid-autumn Festival festivities over the weekend and on Monday, according to the Hospital Authority. Of them, a 12-year-old boy, was in a stable condition in hospital Monday while two others were discharged after treatment. Police said they had received two reports of fire and one arson report related to the burning of candle wax since Sunday.