LOS ANGELES, June 2 (Xinhua) -- Investigators were still trying to determine what caused the fast-moving fire that destroyed much of Universal Studios Backlot in Los Angeles, authorities said on Monday.

    Nine firefighters and a sheriff's deputy suffered minor injuries in the towering inferno, which broke out at 4:30 a.m. Sunday in a narrow alley of an area called the New York City streetscape and burned for more than 12 hours.

    The flames quickly spread to wooden mockups of buildings and destroyed huge chunks of movie history including sound stages and much of the New York City streetscape used for exterior shots. It also burned through the building that housed a mechanical King Kong that delighted tourists on the popular backlot ride, and gutted a video warehouse.

    At the large warehouse, videos of films going back to the 1920swere destroyed, but everything inside the video vault was a copy of material stored elsewhere, and "nothing precious was lost" said Ron Meyer, president of Universal Studios.

    Film negatives and other priceless materials were stored in underground buildings several hundred yards from the fire, he said.

    Studio officials said Universal Studios Hollywood was scheduled to reopen at 10 a.m. on Monday as usual even as the investigation was going on.

    Some firefighters were expected to remain at the scene to douse hotspots. A damage estimate was not immediately available.

    The same area burned in an arson fire in 1990, and was rebuilt incorporating "deluge pipes" designed to dump large amounts of water on fires.

    But the deluge pipes may have been partly responsible for a lack of water pressure during the first critical hours of the fire, county fire chief P. Michael Freeman said.

    Firefighters ran out of water in parts of the backlot at least twice during the firefight and had to pump water from nearby ponds and reservoirs.

    However, fire officials noted that at the height of the blaze, firefighters were pouring 18,000 gallons a minute onto the flames, which would stress any water system.

    Explosions from propane tanks launched basketball-sized debris onto city streets a quarter mile from the fire, hampering the efforts of more than 400 firefighters, said county fire Inspector Darryl Jacobs.

    Bulldozers were removing burning debris from a video warehouse Sunday afternoon when another explosion injured a female sheriff's deputy and a firefighter.

    Eight other firefighters also suffered minor injuries, including burns and smoke inhalation.

    The warehouse contained more than 40,000 videos encased in plastic that sent plumes of dark smoke over the San Fernando Valley that smelled like burning plastic.

    Air quality officials said the smelly smoke did not pose any immediate health problems, but the Air Quality Management District took samples to determine if it was hazardous.