A gas explosion has sparked a fire at a Russian bioweapons facility which stores viruses including Ebola, smallpox and Anthrax.

The blast occurred on Monday after a gas cylinder exploded during scheduled repair work on the fifth floor of the six-story Russian State Centre for Research on Virology and Biotechnology, commonly known as Vector, the facility said in a statement.

No biological material was held in the sanitary inspection room where the explosion occurred, and no structural damage was caused to the concrete laboratory building, the center added.

One worker was taken to hospital and is being treated in intensive care for burns, Russia’s TASS news agency reported. A fire, covering 30 square meters was later extinguished by fire fighters.

The bioweapons facility, located in Koltosvo, in the Novosibirsk region of Siberia, is known for being one of two centers in the world housing samples of smallpox. The US Centers for Disease Control and Prevention is the only other center in the world known to hold live samples of the disease.

Originally, the center was used to develop biological weapons research during the Cold War Soviet era. Now it is one of the largest scientific virological and biotechnological centers in Russia.

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