Russian authorities evacuated people from dozens of buildings in Moscow on Wednesday after a flurry of anonymous phone calls asserting the locations had been mined, RIA news agency reported.
People were evacuated from shopping centers, train stations and a university in Moscow.
Some 500 people were evacuated from the Kazanskiy and Leningradskiy stations.
A source in the emergency services told state-run TASS news agency that over 30 prominent locations including the famed GUM shopping centre on Red Square were temporarily emptied after anonymous telephone threats.
Terrorists have earlier rocked Moscow on two occasions. Emergency services said that police units including explosives specialists and officers with sniffer dogs are examining the buildings.
Threats and evacuations outside the capital also were reported today, in cities ranging from Petropavlovsk-Kamchatsky in the Far East, across Siberia, to Kaliningrad on the Baltic Sea.More news: Hurricane Irma looting: Caribbean Chaos as prisoners escape and looters run riot
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Many were city halls, schools and other official buildings, according to local news reports.
The Interior Ministry and Security Council declined to comment.
According to reports, those responsible for the threats were still not located.
The threats in Saratov region were made anonymously through internet voice calls, the Federal Security Service's (FSB) regional branch said Wednesday.
Major Russian cities have been targeted in previous bomb attacks, most recently in April, when a Russian citizen from the former Soviet state Kyrgyzstan detonated a bomb inside a St Petersburg metro train.