You have made your little bit of the planet just a fractionally better place to be - it might never be the same again.

Lets hope that those two young men think twice next time they are planning violence.

I hope your colleague was not badly hurt, I assume as you did not mention any damage that he was not - however if you had not intervened, who knows what could have happened?

I'm just a natural intervener, never having the chance to think of not getting involved, so it is an interesting thought that you chose to go to help after previous consideration - it makes your reaction all the more commendable.