Seventy-nine people were injured when several blasts at the explosives plant Kristall shook the central Russian town of Dzerzhinsk on Saturday, the Russian health ministry said.
The blasts around midday were heard all over the town of more than 230,000 residents and shock waves smashed or damaged windows in around 180 buildings, city authorities told TASS news agency.
Russian state TV Rossiya 24 showed footage of a plume of smoke rising over the explosives factory.