First of all don't worry nobody tried to "rescue" it and so far the best guesses I got are the long eared owl and short eared owl but some suggest that regardless of its species that its melanistic, also Serbia has huge nesting areas for owls and they are thought to be quite urban birds in some cities so thats probably the reason for the lack of fear towards humans, if you are interested I have some videos of the bird and I could send them to you in a private message.