MOSCOW, September 16. /TASS/. Russian emergencies services have responded to 57 hoax bomb alerts in eleven regions, which triggered evacuation of 21,000 people, law enforcement agencies told TASS on Saturday.

"In eleven Russian regions, including Moscow, 57 bomb threat calls were made on September 16. They were about shopping malls, vital facilities and railway stations," the source said.

"All the 57 facilities have been searched. None of the calls has been confirmed. Transport is not delayed," he added.

Since September 11, a downpour of hoax phone calls has hit Russia. Schools, shopping malls, airports and railway stations have been mostly targeted. On September 13, Moscow alone responded to over 100 anonymous alerts.

Sources told TASS that law enforcement agencies found out that a group of unidentified persons had staged this provocation. The media outlets reported among other speculations that calls were coming from Ukraine (in 2014 hoax bomb threats were coming from Ukrainian numbers) or from followers of the Islamic State terrorist group (banned in Russia). The source has assured TASS that telephone terrorists are being identified and the investigation is underway.