Trump and the GOP would have you believe that there is nothing the government can do to protect you from mass shooters. Just thoughts and prayers are all they can offer. We know this is not true by observing what has happened in every other country in the world that has stricter gun laws.
The man with a gun theory doesn’t fly either. Mass shootings are so unexpected and chaotic, a vigilante with a gun is more likely to get shot by police than stop the shootings. Like in Texas, usually the gunman gets away and is killed by police or kills himself after the incident.