“If the gunman is still at large it’s only common sense.”
That may be true, but is it legal for the government to order people to shelter in place if a gunman is in the area?
Should they go shopping and give him a ride? Seriously? You’re worried about legal?
The government can “order” whatever they want, but that doesn’t mean the orders have any force of law. Not much different that the COVID “mandates” that governors keeps spewing out.