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.

South African police lowered a camera down more than a mile (1.5 km) underground into an illegal gold mine on Thursday to ascertain if any survivors or corpses were still there after a months-long siege by authorities in which at least 78 miners died.

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.