or get a gun and stand firm.
Big city feral populations (read whatever you want into that) hunt in packs too large for even the most prepared among us. A standoff would produce dismal results and would most likely resemble a 'Black Hawk Down' scenario.
Mogadishu is the best way to describe any major western country city today and the best advice for white city dwellers is Get Out Now While You Can! It's no big deal to me if they stay. Not only will they decrease the surplus population, but will inadvertently cleanse the gene pool at the same time as most are liberal A-holes anyway.