Photo taken on Feb. 20, 2014 shows an explosion site on a road in Qiaokou District of Wuhan, capital of central China'a Hubei province. According to the local fire department, three people were injured in a methane gas explosion in Wuhan on Thursday, which collapsed an underground sewage pipe. (Xinhua)

Photo taken on Feb. 20, 2014 shows an explosion site on a road in Qiaokou District of Wuhan City, capital of central China'a Hubei province. According to the local fire department, three people were injured in a methane gas explosion in Wuhan on Thursday, which collapsed an underground sewage pipe. (Xinhua)

Photo taken on Feb. 20, 2014 shows an explosion site on a road in Qiaokou District of Wuhan City, capital of central China'a Hubei province. According to the local fire department, three people were injured in a methane gas explosion in Wuhan on Thursday, which collapsed an underground sewage pipe. (Xinhua)

Photo taken on Feb. 20, 2014 shows an explosion site on a road in Qiaokou District of Wuhan City, capital of central China'a Hubei province. According to the local fire department, three people were injured in a methane gas explosion in Wuhan on Thursday, which collapsed an underground sewage pipe. (Xinhua)

Photo taken on Feb. 20, 2014 shows an explosion site on a road in Qiaokou District of Wuhan City, capital of central China'a Hubei province. According to the local fire department, three people were injured in a methane gas explosion in Wuhan on Thursday, which collapsed an underground sewage pipe. (Xinhua)