Are you experienced in preventing and managing violent incidents? Use your knowledge of behavioral management. How do you react in this type of emergency?

"My immediate response would be to protect myself or the child who was being threatened. If there was a weapon involved I would use force if necessary to remove the weapon from the student. I am not trained in law enforcement, but I am good at acting quickly and taking precautions to protect my students."

You will not be expected to have the perfect expert-level response to a complicated situation like this, but you will be expected to know how to act quickly and follow emergency procedures. If you're not sure what that would look like, be honest. Let them know you are willing to learn what it would take to handle violent situations.