The U.S. Embassy in Moscow issued a security warning Saturday about a potentially imminent “mass casualty event” at the Tsaritsyno Museum Reserve in the Russian capital.
“The U.S. Embassy in Moscow is aware of a credible threat of a mass casualty event TODAY October 31, at the Tsaritsyno Museum Reserve in Moscow at Dolskaya Ulitsa 1, Moscow, Russia 11569. The U.S. government is coordinating with appropriate Russian authorities on a response,” the embassy said in its alert.
The notice urged people to stay away from the Tsaritsyno Museum grounds, remain vigilant and avoid crowded areas.
Tsaritsyno was established in 1775 as a summer residence for Catherine II. Today, the historic site is one of Moscow’s well-known tourist destinations.

A photograph taken on October 22, 2017 shows the Tsaritsyno Palace Museum and Reserve in the South of Moscow. (MLADEN ANTONOV/AFP via Getty Images)
More than two million people visited the museum in 2022, according to remarks made by Moscow Deputy Mayor Natalya Sergunina in 2023. The surrounding parkland is even busier, drawing residents who use the grounds for exercise, recreation and dog walking, The Art Newspaper reported.
The embassy also advised people in the Moscow region to keep mobile phones and other battery-powered devices charged, stay alert to their surroundings and review their personal security plans.
The warning came as the war between Russia and Ukraine continues to intensify.

A photograph taken on October 22, 2017 shows the Tsaritsyno Palace Museum and Reserve in the South of Moscow. (MLADEN ANTONOV/AFP via Getty Images)
On Friday, Ukraine attacked an oil refinery in southern Russia, bringing an end to a two-week halt in strikes on energy facilities. The pause had been brokered by President Donald Trump between the two countries.
A day earlier, Russian drone and missile attacks across Ukraine killed at least 27 civilians, The Wall Street Journal reported.

A residential building damaged from Russian attacks is seen during a local ceasefire related to a humanitarian aid mission in Oleshky, in Kherson, Ukraine, Thursday, Oct. 29, 2026. (AP Photo/Evgeniy Maloletka)
News Outlet has contacted the U.S. Embassy in Moscow seeking additional information.
This is a developing story. Please check back for updates.