A severe tropical storm has swept across southern Taiwan, damaging houses, overturning cars, and toppling many trees after thousands of people were evacuated from their homes ahead of the disaster.Typhoon Tembin sparked heavy floods in towns across Taiwan's southern coasts and left thousands of homes without power on Friday, Taiwan's Central Weather Bureau said.The typhoon dumped nearly 50cm of rain in Pingtung county overnight, leaving four towns flooded in knee-deep brown water. Television images showed rescuers and soldiers navigating through empty streets in rubber boats, while heavy-duty military trucks ploughed through the water to rescue trapped residents.Fallen tree trunks covered roads in the affected areas, and in the coastal village of Tawu, a number of rooftops were blown off by strong winds.A line of electricity poles in the county were also toppled by the storm, cutting off power to tens of thousands of homes.Across the island, more than 50,000 households were without power, according to the state Taiwan Power Company.