St. Joseph Missouri police dept recently had a fatal AD, if that's what it can be called.
During a training session for rubber bullets, some of the trainees took a lunch break and, rightfully, reloaded their guns with duty ammo as they were going offsite for lunch.
When they came back, the student asked another to shoot him in the back with the rubber bullet so he would know what to expect in the upcoming training, but the shooter forgot he had switched back to regular ammo.
I'm not involved in this, just repeating what I read in the newspaper.
Accidental discharges are rare but they happen. If you're around guns long enough, it is very likely you will have or see one.