They were hiding in the corners of the alley where you couldn’t see them. Waiting for an unsuspecting person to happen by.
When one person makes the mistake of walking down the alleyway. The guy seems to be one of the bouncers from a nearby bar about to take a piss on garbage can, when two shadowed figures appear. One looks to the other and they know instantly what to do for they have been doing it for years now. One of the shadowed figures walks in from one side and makes a move closer toward the unsuspecting man now stuffing himself in his pants but accidentally catches himself in his zipper. To cease his screaming before anyone notices from the street nearby, one of the figures swiftly walks up barely making a sound, and comes behind him and gives his neck a quick twist. Though you can still hear the sound of his bones breaking in his neck along with the noise of the bouncers screams still echoing off the wall. The other shadow moves closer a tilts the head back, of the now dead, and slices the throat of the bouncer and pulls the head clear off the body and uses his vein like a straw and sucks up most of the blood from the now stiffening body and then hands it to his accomplice who then finishes the last of the blood in the body. They then discard the now pale body of the deceased bouncer into the trash and then leave to go home.