Schools, government buildings and shopping malls in more than a dozen Russian cities continue to be evacuated four days after local authorities started receiving anonymous bomb threats, the Interfax news agency reported Wednesday.

The evacuations began in Omsk on Sunday and continued in Ryazan that evening. Chelyabinsk, Ufa, Stavropol and Kopeisk received as many as 42 bomb scares in total on Monday.

By Tuesday, the anonymous threats were reported in Perm, Novosibirsk, Yekaterinburg and other cities, forcing the evacuation of an estimated 45,000 people.

The threats in Saratov region were made anonymously through internet voice calls, the Federal Security Service’s (FSB) regional branch said Wednesday.

“The people involved in this are being identified,” the local FSB office’s press service told the FreeNews-Volga agency. Interfax said no explosive devices were found at any of the listed locations.