responsibility of permit holders

[AIronte]

I was in a fairly heated conversation last night with some very liberal, gun hating individuals and this situation arose. I was unable to cite any legal code, so I am asking for your clarification.
The example arose that if a carry holder was at a movie theater and an obvious threat developed, where someone had a firearm and was about to use it; does the carry permit holder have the "Right" or Responsibility" to intercede, possibly with deadly force?

[Safety1st]