Area denial weapons platform like the Metal Storm. All you'd need after that is street sweepers to clean up what was left.
naw... we are still in "kinder, gentler" mode, remember?
10,000 or so folks getting ripped to bits by a firearm or projectile weapons system would be "murdered martyrs", whereas 10,000 rioting idjits who got beat-down by troops using batons would be just bloody fools who got what they asked for.
for some reason, most folks don't consider cudgels to be intrinsically lethal weapons.
If I were in the mood to advocate lethal measures be used against these enemy invaders, I'd favor crop-dusters loaded with kerosene... but we aren't allowed to think in such terms, are we?