Quite frankly, I'm surprised it was so easy to shoot and kill the perpetrators.
What makes you think it was “easy”?
This young Marine was trading fire at close range with an armed and dedicated criminal (although I bet the thugs were thinking they had a lock on the ability to offensively act).
Standing up, attacking the enemy and taking fire is never easy. But, it may be the best thing one could ever do, albeit potentially the last.....
When in a terminal situation, as this likely was, violent force of action and dynamic response is the most likley method to enable survival.
We need more citizens like this young naval officer/former Marine.
Best;