The Actualite newspaper reported, citing provincial governor Richard Muyej Manguez Mans, the victims were miners who had been illegally working at the mine despite the prohibition to do that. The incident took place on Thursday.
The victims' families are currently identifying those killed.
Muyej also called for stopping illegal works at the mine, according to the outlet.
The mine was operated by Kamoto Copper Company, which runs cobalt and copper mines in the area. Last year, the company was forced to suspend its exports of cobalt after traces of uranium were found in its material.