Typically their presence alone is enough to stop anything new from happening. In theory they would only need to use enough violence to defend themselves. That's

Typically their presence alone is enough to stop anything new from happening. In theory they would only need to use enough violence to defend themselves. That's how we got Kent State but in general Kent State was also because the guards in that situation found themselves alone and isolated with little training. In a modern context 60 national guards standing around outside of a downtown highrise with a couple Humvees is unlikely to see any escalation.