Sixteen people were killed in an explosion and fire at a gunpowder and chemicals plant in Russia's western Ryazan province, TASS news agency reported on Friday, citing a source.
The emergencies ministry confirmed 12 deaths in the accident, saying four people remained missing.
TASS quoted its source as saying the accident had been caused by a failure to observe the proper technical process at the facility.
Pictures from the site published by the ministry showed firefighters standing next to a brick building that appeared to have been partly demolished by the blast.
Earlier the emergencies ministry said the fire could have broken out as a result of "violations of the technological processes and safety measures" at the PGUP Elastic factory in the Ryazan region.
The plant in the village of Lesnoye, around 300 kilometers (180 miles) from Moscow, says on its website that it produces industrial explosives.
The emergencies ministry said it first received a report that a fire had broken out at the plant at 08:22 local time.
The ministry said it had deployed more than 170 rescuers to the area.