Six inmates were killed and 35 others were injured when guards opened fire to control a riot at a prison on the outskirts of Sri Lanka’s capital. Two guards were critically injured.

Pandemic-related unrest has been growing in Sri Lanka’s overcrowded prisons. Inmates have staged protests in recent weeks at several prisons as the number of coronavirus cases surges in the facilities.

Police spokesman Ajith Rohana said inmates created “unrest” Sunday at Mahara prison, about 15 kilometers (10 miles) north of Colombo, and officials attempted to control the situation.

But “the unrest situation turned into a prison riot”, he said, adding that prisoners tried to take control of the prison and hundreds attempted to escape. The inmates “reportedly destroyed most of the property including offices inside the prison,” Rohana added.

The guards opened fire, and the clash left six inmates dead and 35 injured, he said. Two prison officers were critically injured.

More than a thousand inmates in five prisons have tested positive for the coronavirus and at least two have died. About 50 prison guards have also tested positive.