A total of 23 people are deemed to be responsible for a coal mine accident in May 2024, which caused five fatalities in northeast China's Heilongjiang Province, an investigation report said on Friday.

The accident occurred on May 20 at the Xing'an coal mine of the Hegang mining company under the Heilongjiang Longmay Group. Nine people were trapped, with four of them later rescued.

An investigation team was established the next day to determine the cause of the accident. According to the report, the direct cause of the accident was identified as the illegal use of grouting pipes to inject liquid carbon dioxide during the disposal of spontaneous combustion hazards. Rubber gaskets connecting the pipes became brittle and damaged at low temperatures, causing liquid carbon dioxide to leak and form high concentrations of carbon dioxide gas -- which led to the asphyxiation of workers.

The accident caused direct economic losses amounting to nearly 9.6 million yuan (about 1.3 million U.S. dollars). The investigation team has proposed suggestions for the handling of the 23 responsible individuals and related units.