Eight people were injured when a stage holding 80 choir members collapsed during a rehearsal for a singing contest at a city theatre in Guizhou province on Saturday, according to state media and local government reports. Bijie municipal government said in a news report that all the injured - including two in a serious condition - had been sent to hospital, and that police were investigating the case. WATCH: Eight injured as stage suddenly collapses during a singing contest rehearsal in China A video of the accident, which was widely circulated on social media on Monday, shows the heavily loaded stage collpasing suddenly and sending choir members tumbling amid screams from the audience and choir. In the video, three choir members were seen rushing to the stage after singing had already started. Seconds later, after one of the three latecomers had taken their place, the stage collapsed. A crash was heard when the stage hit the ground. All 80 choir members were from a local police force, state media said. The choir was rehearsing for a singing contest to mark Labour Day under the theme of "Chinese Dream" - a phrase coined by President Xi Jinping and later promoted by governments of all levels around China. In October last year, 16 music fans plunged to their deaths when a ventilation grate they were standing on collapsed during an outdoor pop concert in South Korea. The victims fell 20 metres into an underground parking area when the grate gave way while they were watching girl band 4Minute. At least a dozen others were injured. In the United States late last month dozens of people were injured when a stage collapsed during a high school rock performance in the state of Indiana, US media reported.