Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]

Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]

Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]

Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]

Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]

Photo taken on Aug. 2, 2012 shows the scene of an explosion in Nanjiang county of southwest China's Sichuan Province. One killed, 25 people were injured, including 3 seriously, in an explosion that has ripped through an office building in Sichuan Province, local authorities said Thursday. An initial investigation indicated that the blast was caused by a natural gas leak, the county's publicity department said in a statement. [Photo/CFP]