Let’s review basic firearms safety. This sniper violated 2 of the 4 rules of gun safety (read linked article for details).
1. Keep your finger off the trigger until you have made the decision to fire.
2. Positively identify your target, and what lies beyond.
The other 2 rules are:
3. Don’t point your muzzle at anything you do not intend to destroy
4. Every gun is loaded unless you personally verify otherwise.
That’s a big oops! I am painfully aware that even trained professionals make mistakes with firearms even those with training as instructors ! Constant vigilance is the watchword when handling a firearm. This guy is going to be lucky to keep his job.