It’s sad the USA is the only nation in the world that thinks it’s normal to traumatize children and adults with active shooter drills because no one has the wit to understand that small arms and untrained civilians have no business being connected. There is no justification for the utterly insane US gun policy, no matter how many times NRA shills twist the 2nd Amendment out of context or pretend their tiny little weapons are their “protection” against government over-reach.
The one thing I would add is that your tips are correct. Run is always the best option; hide in place a poor second (now you’re a static target and much easier to kill); third is essential if required: act with overwhelming speed and force and don’t stop until the assailant is incapable of ever again being a threat. But mostly be alert. People spend far too much time heads-down over their phone and far too little time being aware of their surroundings.