They don't have to order the army to shoot on sight, just have them take up a defensive perimeters around them and push them back/disperse them.
That's how we delt with the native americans who took up arms and tried to defend their area when the city in question wanted to raze part of it to add an extention to the local golf course a couple of years ago. After a couple of days they gave up and we got a new golf course.
