The gas leak was caused by both nitrogen sulfide and carbon monoxide. According to the county government official, “villagers said they could feel the heat 200 meters away from the site.” Another major incident occurred in October 2019. A major explosion occurred at one of Yanchang Petroleum Group’s drilling plants. There were 5 casualties, 5 injured and 3 others missing. The reason for this incident according to investigators was caused by the testing of a new method of drilling using thermal technology that would increase oil or natural gas output. The incident took place 40 km east of Yan’an city in Shaanxi Province, and is considered one of the oldest plants in China. After the report of the incident, the provincial government could not be contacted for additional comment and it is currently unclear if the plant is still operational.