That sounds a bit scary @super_ram, not the sort of thing you want to witness is it?
It reminds me of an incident years ago when I was a youth, a friend of mine was running along the pavement in Sneinton, I can’t remember why he was running but it was completely innocent, he became aware of two men running behind him and shouting so a bit frightened he ran faster but so did they and eventually they caught up with him and it turned out they were plain clothes policemen they arrested him because he resembled someone who had just committed a serious offence, he was cuffed and hauled off to the police station where thankfully he was able to prove his innocence but a very scary thing to happen to him.