Peru is assigning the military with the task of regaining control of a mineral-rich area of the country’s northern highlands after 13 gold miner were kidnapped and murdered.

Army troops who were previously supporting police in the province of Pataz will now take control of security, Peruvian President Dina Boluarte told reporters in Lima on Monday. Mining activity in the area will be suspended for 30 days.

She spoke after 13 bodies were discovered in a mine shaft over the weekend as criminal groups step up a wave of terror over control of the precious metal in the area. The deceased were working as guards at a small mine that is a contractor to Compania Minera Poderosa, one of Peru’s largest gold producers. At least 39 workers have been killed in recent years in Pataz, Lima-based Poderosa said Sunday in a statement.