Powerful typhoon kills 20 in southern China, swipes Hong Kong HONG KONG (Reuters) - A powerful typhoon hit Hong Kong and the southern China coast on Monday, killing at least 20 people on the mainland, crippling power lines and causing flooding and gale force winds. Typhoon Usagi, the strongest storm to hit the Western Pacific this year, began pounding the Asian financial center late on Sunday. More than 370 flights were canceled. 8 signal warning remained in force early on Monday, with financial markets closed for at least part of the morning. The weather observatory said the storm had weakened from "super" typhoon status and that it would consider lowering the warning signal before 10 a.m. China's National Meteorological Centre issued its highest alert, with more than 80,000 people moved to safety in Fujian province and authorities deploying at least 50,000 disaster-relief workers, state Xinhua news agency reported. At least 20 people were killed on China's southern coast, television reports said, including 13 in Shanwei in the eastern fringes of Guangdong province. The victims included people hit by debris and others who had drowned. One man was killed by a falling window pane. "It is the strongest typhoon I have ever encountered," Xinhua quoted Luo Hailing, a gas station attendant in Shanwei, as saying. So terrible, lucky we made preparations. Winds of more than 180 km/hour (110 mph) were recorded in some parts of southern China, toppling trees, cranes and blowing cars off roads in some areas. The storm had earlier brought down three major power lines in coastal Fujian, cutting off electricity supplies to about 170,000 households, Xinhua reported. In Guangdong province, a major base for Chinese nuclear power, the Daya Bay nuclear power plant just east of Hong Kong had initiated emergency response schemes, Xinhua said. Four of the six power-generating units at the plant had been ordered to operate at reduced load. Airlines canceled flights to cities in southern Guangdong and Fujian, while shipping was suspended between China and Taiwan, state media said. Despite earlier warnings the typhoon could pose a severe risk to Hong Kong, the city suffered only minimal damage, including toppled trees. There were no fatalities in the city. The Hong Kong Exchange delayed the start of trading on securities and derivatives markets due to the typhoon. There will be no trading in the morning if the typhoon signal remains at 8 or higher at 9 a.m Hong Kong time (0100 GMT), with trading suspended for the whole day if storm signal 8 is still up at noon. Schools, businesses and non-essential government services will also close while storm signal 8 remains hoisted. Usagi lashed the east and south coasts of Taiwan on Saturday after slamming into the Philippines' northernmost islands, where it cut communication and power lines and triggered landslides. Reporting by James Pomfret; Editing by Paul Tait