I agree, Jim. Rampant racism is obviously a huge catalyst in both countries.
Racism occurs in UK too of course, and the weapons of choice are usually knives, as I understand it. The thing is, while dangerous, knives, although illegal in UK, haven't the same killing power as automatic rifles.
I have watched an interview with black young men in London on TV, and they too stated they carried knives for 'protection'. They were basically very afraid.
But it could just as easily be Catholics v Protestants (as was the case in Northern Ireland)
It all boils down to Hatred and Fear. The only remedies are Love and Reassurance. But someone has to make the first move, thus making themselves vulnerable. I don't think I'd be brave enough to be honest.