A HUGE structure used to store film-making material, props and carpentry at the Shaw Brothers Studio in Clear Water Bay was gutted by fire last night. Initial estimates indicated that the damage could be as high as $10 million, but the cause of the blaze is not yet known. Flames shot as high as two-storeys, tearing into the tin-sheet structure and collapsing the Chinese-style roof. The action for once proved real, as actors, some fully in ancient Chinese ceremonial dress and others dressed as nurses, mingled with the spectators. Other TVB staff saved documents from the production department, within metres of the blaze. Firemen had difficulty laying hoses and maintaining water pressure, as the film studio sits on top of a hill. Some hoses were connected to hydrants in the adjacent TVB City. Fire chiefs said later they had regularly staged drills at the site, knowing that the huge amount of wood and polystyrene kept there made it a fire risk. Kowloon East Senior Divisional Officer Lau Shu-lam said no injuries had been reported. ''As far as we know, no one has been hurt, but this was a very big fire. We have regular drills here because it is a known fire risk. The building was full of combustible material such as wooden props.'' Staff at TVB City said they believed all studio workmen had left before the fire broke out shortly before 8 pm. The fire was upgraded to the third alarm at 8.05 pm and raised again to fourth alarm at 8.42 pm, by which time 25 fire engines had arrived. By 11.10 pm, firemen had encircled the fire and 40 minutes later it was put out. Police have still not solved a suspected arson attack on neighbouring TVB City on November 16, 1991. The ferocity of that blaze, which started at 2.34 am and was given the fire service's highest emergency rating of five alarm, melted iron girders and buckled corrugated tin sheets. The largest building destroyed in the TVB City fire was a warehouse known as the Prop Store, containing mainly wooden and styrofoam fittings, panels and furniture. The other three similar, but smaller, buildings destroyed in the 1991 fire were on the side of a hill across a private concrete road leading to Sir Run Run Shaw's summer house, only a few metres from the fire.