At least two people were missing and 22 were injured on Saturday in blasts at the explosives plant Kristall in the central Russian town of Dzerzhinsk.
A health ministry official said that most of the injured have fragment wounds.
Dzerzhinsk is close to the city of Nizhny Novgorod, about 400 kilometers east of Moscow.
The Kristall scientific institute is one of the major Russian developers of explosives technology for military and civilian use.
The building was partially destroyed and fire broke out at the facility.
Rossia 24 TV showed smoke rising from the plant.