Police say the death toll in a monthslong standoff between authorities and miners trapped while working illegally underground at an abandoned gold mine in South Africa has risen to at least 87.

The South African government has launched a rescue operation at an abandoned gold mine in the country’s North West province, where at least 109 men have died, a group representing the miners said, after local authorities cut off vital supplies in a dramatic bid to crack down on the country’s illegal mining trade.

Arguing that the miners had entered the mine without permission, authorities reportedly cracked down by cutting off their access to food and water.