Firemen rescue at the scene of an accident on Hongqi Road in Zhuzhou, central China's Hunan Province, May 17, 2009. Four bodies were pulled out of the debris of a collapsed viaduct in Hunan Province, local sources said Sunday. More digging machines were summoned for rescue work and the cause of the accident is not known.(Xinhua/Long Hongtao) Photo Gallery>>>

    ZHUZHOU, Hunan, May 18 (Xinhua) -- Two more bodies were retrieved from the debris of a collapsed viaduct in central China's Hunan Province, bringing the death toll from the accident to six, the rescue headquarters said Monday morning.

    Another 17 people were injured and rushed to hospital.

    About 550 rescuers are using more than 30 digging machines to search for buried people, but detector signals indicated that there are likely no signs of life in the debris.

    Rescuers have pulled out nine vehicles trapped in the rubble.

    About 200 meters of the viaduct, supported by eight pillars, collapsed at 4:24 p.m. Sunday in the Hongqi road of downtown Zhuzhou city, burying the road beneath and affecting 27 vehicles passing by.

    The rescue operation moved slowly as trunks of the collapsed viaduct are too big to clear.

    The municipal public security bureau said Monday that police have detained people initially held responsible for the accident but did not offer any details.

    Officials with the provincial government are investigating the accident. A senior officer with the state work safety watchdog will soon arrive for the investigation.

    The viaduct, which came into use in 1995, was recognized as the first urban flyover in Hunan. It was 2,750 meters long and eight meters tall.

    As the bridge spans over the bustling Hongqi Square and used to cause traffic congestion in the area, the city government closed traffic on the viaduct on May 5 for dismantling.

    Workers had exploded part of the viaduct and planned to explode the collapsed section on Wednesday.