Go Mags! Use pumper fire trucks and throw-in a couple of bottles of liquid soap to hose them down with. It’ll not only clean them up, but if they’re not wearing goggles, they won’t be opening their eyes anytime soon. And for good measure, shoot tear gas into the crowd.
There’s going to be a lot of sick people among them. We know this because some turned back they got sick with on the way... so whatever they have will of course spread among them over time.