In the news

I have no clue how this is related to my point.

Again:

I would happily shoot people setting fire to places where children sleep to stop them.

Would I be happier with the person being caught the following day, with a stern prosecution based on the increased use of technology, caught through his or her own blog or facebook images - while my son is in the mortuary ?

No, not at all.

If I had access to a gun I would use it against attackers in this scenario.

Much like your example of jumping in front of a train to save something you love, I'd be attempting to save what I loved from the burning building rather than wasting a few potentially life saving seconds drawing a weapon on someone. That was my point.