Fear swept through Borough Park, Brooklyn, as soon as the news got out: A young man was randomly assaulted by strangers early Friday morning, and the attack was possibly part of the so-called Knockout Game.

Four men were arrested, but on Friday night only one was charged and the others were released.

The attack added to a growing log of reports of such crimes in the Northeast and beyond. Young assailants were randomly picking unlucky targets and trying to knock them out with just one punch.

Yet police officials in several cities where such attacks have been reported said that the “game” amounted to little more than an urban myth, and that the attacks in question might be nothing more than the sort of random assaults that have always occurred.

And in New York City, police officials are struggling to determine whether they should advise the public to take precautions against the Knockout Game — or whether in fact it existed.