My son and I are at odds about the proper response to this type of assault. Part of our difference is that he usually travels alone and I with spouse and/or MIL. His plan is full retreat if possible while mine is fort up at the first defensible spot where I can cover 180* or less. Another point is that he carries a small 6-7 shot 380 w/1 extra mag and I carry a full size 9mm 15 shot with at least 1 extra mag. In addition, he's 32, 6'1",180 and I'm 60ish, 5'9", and 160. If push comes to shove and an attacker was injured, I'd be on much more legally defensible ground than he(his thoughts-not mine)especially if I had 1-2 dependants to protect.
I don't think these "mobs" would push the issue with an armed victim but that's an unknown until it happens. I might outrun a teenager but seriously doubt it and I sure won't turn my back for long. If there's 50 of them I'll get overwhelmed but the last thing I do will be slide my pistol under a car and there won't be 50 leaving the scene(unless carried).