Also, North Korea is very high on discipline. They've been known to sentence people to work camps/ death sentence for as little as making the wrong radio announcements where Americans/South Koreans could hear it. I consider an accidental misfire quite unlikely.
Not only that, if you escape they'll put your entire close family (about as far as cousins and uncles I think) into prison camps. There was a story I read about a guy who made a joke about Kim jong-il's height when drunk and was sent to a prison camp, and within the camps it's even worse - people being shot multiple times and killed by guards for trying to pick up two nuts from the ground to eat because of starvation. Then you get into the human experimentation stories (according to an escapee who claims to have been an officer in a camp and supervised gas chambers and poisoning men, women and children to death) and forced abortions and rape and torture and abuse etc. It's even more screwed up when you hear about the kids born in these camps and it's all they know. That officer I saw in a documentary was also pretty frank about what he did - he believed then, in his own words, that the prisoners weren't human/were subhuman. A bit like the attitudes of imperial japanese soldiers towards POWs.
If even 40% of that is true, we're going to see a lot of bad shit when the DPRK finally collapses and we gain access to the truth. If you want more information, read a book called "The Aquariums of Pyongyang" by Kang chol-hwan, or perhaps "Nothing to Envy" by Barbara Demick.