An explosion sparked a fire at a Russian research facility that is reportedly one of two places in the world that houses live samples of the smallpox virus.
A gas canister exploded Monday at the Russian State Center for Research on Virology and Biotechnology in Siberia, the facility said in a statement. Officials there insisted there was no threat of contamination.
The center is also known to hold other dangerous samples such as Ebola, HIV and anthrax.
The statement said the explosion, which injured one person, occurred in a sanitary inspection room.
The Russian news agency Tass said no hazardous material was being held in the inspection room.
Russian authorities refused to release any other details about the explosion at the facility, which was used to develop biological weapons during the Cold War.
The blast comes just weeks after five scientists were killed after a mysterious explosion at a missile testing site in August.