An estimated 60% of Zijin Mining’s Colombian gold mining operations have been halted amid attacks on workers by illegal miners working for one of Colombia’s many crime gangs.

The Buritica mine is Colombia’s largest gold mine and the first large-scale underground mining system in the country. The mine was originally owned by Canadian Continental Gold but was acquired by the Zijin Mining Group in December of 2019 for $1 billion USD. Zijin is a Chinese-based mining company with operations all around the world; the Chinese government being the company’s majority shareholder.

Juan Calmilo Narina, the president of the Colombian Mining Association (ACM) guild, told workers they should wear body armor and ensure they have police protection while conducting operations to ensure their safety from both shootings and bomb attacks utilizing cylinders of propane gas as explosives.

“This doesn’t happen anywhere in the world; mining company workers need to go to their work areas with body armor,” Narino told journalists on Thursday. “The immediate intervention by the Colombian state is urgent, so this doesn’t happen again.”

Many tunnels within the Brutica mine are controlled by the Clan del Golfo crime gang, which takes a 10% cut from the illegal miners. These illegal miners often work in extremely dangerous conditions, which have previously led to large-scale protests from local workers over entrapments within the mine due to cave-ins following the use of dynamite.

Aside from the fears for worker safety, some officials worry that the illegal mining operations may adversely affect the local environment, including poisoning the local watershed with mercury, which illegal miners use to separate gold from mined dirt.

The rise in illegal mining has also led to a population explosion in the region, with an estimate of 5,000 people arriving in the region to work for Clan del Golfo.

Attacks on mines are no rarity in Colombia, with four other Colombian mining companies closing production due to similar attacks on their own mines. Problems at Buritica risk 4,200 jobs and $95.4 million in tax and royalty payments, Narino said.