I had a similar conversation with my lib sister a while ago. She felt that her life would be in greater danger if lawfully armed civilians engaged a murderous maniac in a shootout. I asked her if she was hoping that the unopposed kook killing everyone was going to run out of ammo before he got to her.
I read somewhere that the terrorists reloaded FOUR times (so much for hi-cap mag bans). She may have a chance though if she lives in NY state where mags higher than seven round capacity are banned.