The thing is, from my experience, this is
not always a harmless situation. Seeing this reminds me of those times and makes me think of mitigation strategies to make sure I'm safe. (See that look on her face? My first read of that is 'Don't make eye contact, don't acknowledge them or they'll follow you around the block and into any smaller streets and if you're unlucky back to your house.')
The fact that there's so many groups of seemingly unrelated guys in the picture is good though, they will keep each other in check and if there's trouble some of them will step up to help. If you can be sure there won't be a small subset of them following you one minute later, it could be worse. They seem to be on some sort of break, so you're probably safe from that. The guy with the scooter looks the most problematic, so keep an eye on that one without looking at him.
This is a normal though process for many women. In almost all cases it's perfectly safe, but you need to catch the one where it isn't. Are you telling me this is irrational?