What to do if you receive a fake 'summons' and a demand to transfer money

I read that a new fraud scheme has appeared in Kyiv: people, especially pensioners, receive calls supposedly from police officers or other authorities, are accused of criminal offenses for ordering medicines online, and are sent supposedly official summonses demanding they come for an 'interrogation.' Then, they are forced to transfer money to some accounts 'for verification' or hand over cash through a 'courier.' If I or any of my relatives receive such a threat or a message in a messenger, what is the legal course of action in this situation? Where should I turn to and how can I protect myself from such fraudulent activities to avoid becoming a victim?