Tanzanian police said on Friday they had arrested 13 suspects in connection with last month’s killing of five employees of a gold processing plant in Tanzania’s northwestern region of Shinyanga.

Mihayo Mshikhela, Commissioner for Special Police Operations, said police had also seized a firearm with two rounds of ammunition, a machete and five motorcycles used by the suspects to ambush the small-sized gold processing plants in the region.

“Police have succeeded in dismantling a syndicate of criminals that was engaged in ambushing small-sized gold processing plants,” Mshikhela told a news conference in Shinyanga region, adding that the arrests were made during a special operation that lasted for a week.

On June 30, at least five employees of a gold processing plant in Shinyanga region were slashed to death by machete at dawn by a group of unknown assailants.