June 16 (Reuters) - Gas pipeline infrastructure facilities operator China Gas Holdings Ltd (0384.HK) said on Wednesday it was investigating the cause of a gas pipeline explosion in central China over the weekend, and results were so far uncertain. The blast, which occurred on Sunday in the city of Shiyan, in Hubei province, reportedly killed 25 people and injured more than 100, according to reports by state broadcaster CCTV as of Monday. read more Shiyan Dongfeng Zhongran City Gas Development Co Ltd, a non-wholly-owned unit of China Gas, is one of the gas suppliers for the area. In its statement, China Gas said it had established an emergency response group to work with government departments on emergency measures and to investigate the cause of the incident. The Hong Kong-listed company"s shares plunged about 15% on Tuesday prior to a trading halt. China Gas said it had applied to the stock exchange for its shares to resume trading from Wednesday morning. China Gas added that the operation right for piped gas in that area was originally owned by a gas company under Dongfeng Motor Corp, which in 2015 contributed the gas pipeline network while a China Gas unit contributed cash to jointly establish Shiyan Dongfeng, the unit in question. Reporting by Rashmi Ashok in Bengaluru; Editing by Jacqueline Wong Our Standards: The Thomson Reuters Trust Principles.