Firefighters work at the accident site after a gas explosion occurred in an underground shopping street in Shenyang, capital of northeast China's Liaoning Province, March 4, 2013. More than 20 workers were injured in the explosion triggered by a gas leak from underground pipelines at a construction site in the underground shopping street in front of a shopping mall on Monday morning. Some 40 workers were at the scene at the time of the explosion. [Xinhua]

Injured people receive medical treatment in hospital after a gas explosion in an underground shopping street in Shenyang, capital of northeast China's Liaoning Province, March 4, 2013. More than 20 workers were injured in the explosion triggered by a gas leak from underground pipelines at a construction site in the underground shopping street in front of a shopping mall on Monday morning. Some 40 workers were at the scene at the time of the explosion. [Xinhua]

An injured man receives medical treatment in hospital after a gas explosion in an underground shopping street in Shenyang, capital of northeast China's Liaoning Province, March 4, 2013. More than 20 workers were injured in the explosion triggered by a gas leak from underground pipelines at a construction site in the underground shopping street in front of a shopping mall on Monday morning. Some 40 workers were at the scene at the time of the explosion. [Xinhua]