A rainstorm swept across the city last night, triggering a spate of power interruptions citywide and calls for help from people stranded in lifts. The Observatory issued a red rainstorm warning at 12.40am, meaning that more than 50mm had fallen over large parts of Hong Kong in an hour. About 20 residents in Tung Hei Court, Shau Kei Wan, fled their homes when lightening hit a tree, setting off a small fire in an electrical switch room. At least one report of flooding was receiving from residents in Wang Toi Shan San Tsuen, Yuen Long. No injuries were reported.