Ten illegal miners have been reported dead after the mine they were in collapsed in Mozambique’s northern Cabo Delgado province, an official said on Tuesday.

The collapse occurred on Monday near a concession in Montepuez owned by British mining firm Gemfields.

Ramiro Guitar, the director of mineral resources and energy disclosed that about fifteen people are believed to have been in the mine when it collapsed. Guizare added that two people have been rescued.

Mozambique has many illegal miners, and they are popularly known as “garimpeiros,” and Montepuez is rich in rubies. Gemfields in January agreed to pay 5.8 million pounds to settle claims brought against the company by 273 Mozambicans.