In the "what if" scenario the OP draws, unless your vehicle's equipped with something belt fed, you're SOL. Once your Glock 19 runs dry, the crowd will get you.
Actually no. Pop a couple and the probability the crowd starts running is very high. They're punks, not trained military.
Best idea? Stay away from anywhere trouble might bubble up. Failing that, find alternate routes to/from where you need to be.
That, of course, is the best option.