Gunmen have killed at least 20 people at a coal mine in Balochistan province in southwestern Pakistan, according to local police.

The attackers stormed the workers’ accommodation at the Junaid Coal Company mines in the province’s Duki district in the early hours of Friday morning, rounded the men up and opened fire.

A hospital in Duki has received 20 bodies and is treating six injured people, reported Reuters.

The workers were attacked with heavy weapons, including rocket launchers and grenades, police said, while one survivor described seeing a drone overhead.