I just saw 6-7 players called "hdnfgdt" and such

I guess those are bots. But is it possible several bots to be launched from one account?

Yes bots. no, they are different accounts. And yes, kill them all.

And please report them, or at least one of them and mention there are others with them, if you can. If its easier for you, send in a screenshot via the "Ask a Question" link so we can nail 'em. :)