I saw three kids about 9 to 11 year old damaging a seating area outside a library in the street. I didn't see any parents or security so I told the kids that this was not a good way to behave and politely asked them to stop the damage.The kids ran up the nearby stairs to their mum, grand dad and another kid around 12 year old. The mum started hurling abuse at me in the most dreadful way. I tried to explain what had happened and the mum just carried on swearing. and then the grand dad joined in and threatened me. They hurled insults at me at the top of their voices called me all the names they could think of using as many swear words as they could think of. The 4 kids urged their mum and grand dad on and laughed when the mum and grand dad told me off and called me horrid names. I walked off in order to calm the situation down. They followed with threats and the grand dad came right up to my face scowling and threatening me. Meanwhile the kids laughed. All I was trying to do was to protect public property and as I could see no parents or security I politely asked the kids to stop.
I don't know what to do now if I saw other nasty things happening. What should I do, for example, if I saw kids beating up an elderly lady and their were no parents or security around? Was I wrong to intervene?