An explosion sparked a fire Monday at a Russian biological research center known for being one of two places in the world that holds live samples of the smallpox virus.

A gas cylinder exploded on the fifth floor of a six story laboratory building at the Russian State Centre for Research on Virology and Biotechnology in the city of Koltsovo, the center said in a statement Monday. A sanitary inspection room was being repaired when the blast hit the center, also known as VECTOR, causing a fire that spread 30 square meters.

No biohazard material was held in the room where the explosion occurred and only one person was injured, according to the statement. Russia's news agency TASS reported that an employee of a construction contracting organization was taken to the burn center in the city of Novosibirsk with burns to the lower extremities and is in intensive care.

Glass was shattered in the building according to TASS, but the center said there was no damage to the concrete reinforced structure.Nikolai Krasnikov, the town's mayor, stressed to TASS that the incident posed no threat, biological or otherwise, to the population.

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VECTOR was founded in 1974 to study deadly diseases like anthrax and develop biological weapons during the Cold War era, but the center now focuses on diagnosing and treating infectious diseases like swine flu, HIV and Ebola, according to TASS.

The lab is one of two places in the world that houses the live smallpox virus; the other is a lab at the Centers for Disease Control and Prevention in the United States. The site was inspected by the World Health Organization in 2016 and was found to meet international levels of biosafety and biosecurity for its smallpox research and storage but inspectors "requested further work on some issues."

A VECTOR researched died in 2004 after pricking herself with a needle carrying the Ebola virus, the Moscow Times reported, which raised concerns about the lab's safety and secrecy.

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