An official investigation into a deadly mine dumping site collapse in Lufeng city, Chuxiong Yi autonomous prefecture, Yunnan province, has concluded that long-term illegal operations and regulatory failures led to the disaster, with 26 people now facing judicial or disciplinary action.

The collapse occurred on May 5, 2025, at a dry-stack tailings facility operated by Jianfeng Trading in Wuding county. Five people were killed in the incident, according to local authorities.

An accident investigation report released by Chuxiong's emergency management bureau on Wednesday has confirmed that five people related to the incident were transferred to judicial organs, four of whom have been arrested or prosecuted.

It also referred 21 public officials with relevant issues to the corresponding discipline inspection and supervision departments for investigation.

Investigators concluded that the disaster was caused by the company's prolonged illegal extraction and piling of tailings, which resulted in slopes that were excessively high and steep. Over time, continuous seepage of water through the tailings led to infiltration and softening, ultimately triggering a collapse.

The report said failures in oversight by relevant regulatory departments, as well as negligence by local Party and government authorities, allowed major safety risks to persist for an extended period.

It classified the incident as a production safety responsibility accident, stressing that preventable hazards had not been addressed despite clear warning signs.