The headline is a bit inaccurate:
Henshaw said two men were largely responsible for subduing the would-be bank robber. One, a customer, happened to have a concealed-weapon permit. He went to his vehicle, retrieved his weapon and had Johnson at gunpoint while waiting for law enforcement, Henshaw said.It's not clear why he wasn't carrying his weapon instead of storing it in his vehicle. But in Iowa, one has to have a permit to carry if you wish to legally have a loaded weapon in your vehicle. It's one of many laws that don't make much sense here.
Kudos to the citizens who "took the law into their own hands" and ended what could have been a tragedy and stopped a crime before the cops arrived.