According to the media, these notices were placed on numerous buildings across the city of Rostov-Na-Donu by prankers and contain random numbers of deviants found. The phone numbers mentioned in the notice belong to the police and one of the city goverment officials.
The city's administration has claimed that they have never issued such notices, which is believable because the goverment notices would at least have the city herald on them. To those who have found such notices on their houses it was recommended to report it to the police.
So, I presume this arrogant provocation was done by the prankers who intended to worsen the reputation of our country (not for the first time, actually) and maybe even belonged to an LGBT organization themselves.