A landmark skyscraper in downtown Shenzhen started to shake for unknown reasons on Tuesday afternoon, leading to an emergency evacuation of thousands of people. The Shenzhen Emergency Management Bureau said it had received reports that the SEG Plaza, a 20-year-old, 79-floor building with a height close to the Empire State Building in New York, was wobbling and that relevant authorities were still investigating the matter. The bureau said that there had not been an earthquake in the city when the shaking took place at around 1:50pm. The local weather report also showed a wind speed in Shenzhen of around 27km per hour, a speed unlikely to cause the shaking of high-rise buildings. The SEG Plaza is the fifth-tallest building in China’s boomtown and is at the heart of Huaqiangbei, the world’s largest bazaar of hardware and electronics components. According to video clips on Chinese social media, many people were seen rushing from the building. There have been no reports of casualties, injuries or property losses. Chen Wei, a hard drive vendor at the SEG Electronics Market attached to the SEG Plaza, said he had not felt any shaking but was told to leave the building with others. “One of my friends was in the [high rise] building and noticed that the water bottles on the desk started to shake,” Chen said. Chen said there were also evacuations of nearby buildings and road traffic was temporarily blocked. Ji Jialin, a manager at Segmaker Space located on the 14th floor of the Plaza, told the South China Morning Post that the emergency happened during her lunch break. “The shaking didn’t seem strong from the 14th floor ... we all escaped with others by taking the stairs,” said Ji. By 6pm ground traffic surrounding the Plaza had resumed but barricade tapes were still in place and many people could be seen taking pictures of the building from the outside. Lu Jianxin, a chief engineer at China Construction Science and Industry Corp, was quoted by local newspaper Shenzhen Special Zone Daily on Tuesday as saying that the shaking could have been caused by “resonance” effects. “If there was no earthquake today, it would be unusual for SEG Plaza to have such a situation,” Lu was quoted as saying. “Judging from the currently available information, this could be an accidental frequency coincidence, that is, resonance.” Lu added that it would be down to the official investigation to confirm the reasons behind the shaking. Experts said it was rare for buildings to wobble in a way that people can sense. The building remained closed to entry on Tuesday afternoon and fire trucks were parked outside the building. A police officer told the Post said she had not received any message about when the building would reopen. The building is owned by Shenzhen SEG, a listed company controlled ultimately by the Shenzhen state-owned asset supervision commission. The share price of Shenzhen SEG lost 1.66 per cent on Tuesday.