Except their gun laws are pretty permissive and from reading the article it seems like there were plenty of opportunities for that “good guy with a gun” to have stopped it before the police caught up with him.

Remind them that the same day as Sandy Hook there was a mass stabbing attack in a Chinese school. No one died. https://en.m.wikipedia.org/wiki/Chenpeng_Village_Primary_School_stabbing

Knives are less deadly than guns. These are all tragedies but they are not comparable in outcome.

Anecdotes aren’t science, though. So rely on the science that says guns are dangerous and don’t make us safer. https://www.hsph.harvard.edu/hicrc/

Browse around gun owners, you won’t be happy.

I considered it, but have decided to go with "I didn't know Reefer Madness was real."

They ignore that with a gun, the kill count would have been 10x higher

This guy broke into homes to stab people.

Statistically, you are more likely to die at home than anywhere else.

https://gh.bmj.com/content/6/9/e006766