(CNN)An explosion has caused a fire at a Russian biological research facility that's one of only two centers in the world known for housing samples of the smallpox virus.
The blast occurred Monday during repair work of a sanitary inspection room at the Russian State Centre for Research on Virology and Biotechnology, known as Vector, near the Russian city of Novosibirsk in Siberia, the center said in a statement.
One worker was injured in the incident and is being treated in intensive care for burns, Russia's TASS news agency reported.