The US Embassy in Moscow warned of the threat of an event "that may cause mass casualties" today at the Tsaritsyno Museum Reserve "The US Embassy in Moscow has become aware of a credible threat of an event that may lead to mass casualties today, October 31, on the grounds of the Tsaritsyno Museum Reserve in Moscow at 1 Dolskaya Street," the statement said. "The US government is coordinating its response with the appropriate authorities of the Russian Federation."