An explosion at a power station in China killed at least 21 people and injured five more today, the official Xinhua news service reported.The blast, which local media said happened when a high-pressure steam pipe burst, came a day before the first anniversary of giant explosions that killed at least 165 people in the northern port city of Tianjin, reports AFP.The latest incident occurred in Dangyang, in the central province of Hubei, and rescue efforts were underway, reports said.The local government said it was investigating the cause of the accident.Newspapers said the company operating the plant was registered for power generation and sales of slag ash and petroleum products.Industrial accidents are common in China, where safety standards are often lax.Earlier this summer more than 130 people were taken to hospital after chemicals leaked from a plant in eastern China.