An elderly woman and her son died in hospital last night after a row in an overcrowded flat apparently developed into an early morning arson attack. Tang Yee, 78, and Li Fuk-hing, 60, died in Queen Mary Hospital. A 90-year-old woman was fighting for her life after the blaze, which left her with serious burns. The woman died at 9.30pm and her son at midnight. The fire, in a sixth-floor flat at Yue On House, Yue Wan Estate, Chai Wan, broke out shortly before 6am when another tenant allegedly set fire to paraffin-soaked newspapers. Five people were in the flat. Tenant Li Hung-chiu, 34, told police he was awakened by smoke and saw a fellow tenant next to a stove in the living room, with fire blocking the exit. Eastern divisional officer Wong Shiu-hung, from the Fire Services Department said: '[Mr Li] climbed out of the window to escape then scaled down to a floor below and entered a fifth-floor unit. 'He ran back to his burning unit and used a fire hose reel to battle the blaze.' A neighbour said the flat became engulfed in flames, and thick smoke spread to the corridor. 'As other residents used a hose to fight the blaze at the front door, I stood on a chair and broke a ventilation window in the corridor and poured water into the burning unit through the window,' the neighbour said. 'Others used a hammer to break the padlock and opened the front door.' They were relieved by firefighters who arrived within five minutes. A fire officer said three people suffering from serious burns were found in the flat. Another elderly man, overcome by smoke, was found trying to climb out of a window but was stopped by firefighters. Firemen put the blaze out at 6.12am. Three men and two women were taken initially to Eastern Hospital. Mr Li was treated for leg injuries and discharged. Tang and her son were declared dead after being transferred to Queen Mary Hospital with Leung Yu, 90, who was in critical condition. A 75-year-old man was under arrest last night at Eastern Hospital, where he was in stable condition. Police Superintendent Man Chi-hung said the incident was apparently provoked by a longstanding dispute between the elderly tenants over various problems. He said the arrested man, Ms Leung and Tang were the registered tenants of the flat and police were investigating whether Li Hung-chiu and Li Fuk-hing were illegal occupiers. Last night, police classified the case as murder and arson.