An explosion at a Russian factory in the Urals producing ammunition and weapons for the military has left at least 10 people dead, reports say. Witnesses described seeing explosions and fireballs at the Plastmass military plant in Kopeisk, near the city of Chelyabinsk. Regional governor Alexei Teksler did not specify which factory had been hit but confirmed the death toll. The Tass news agency reported that 18 other individuals have been injured in the blast. Authorities have not yet provided details on the cause of the explosion, but Teksler stressed that there is no talk of a UAV (drone) attack. A day of mourning has been announced, and investigators have opened a criminal inquiry into the incident. Teksler stated that the fire in Kopeisk has been put out.