I wasn't involved in an actual shooting, but I had a cop point a loaded gun at me during a lockdown for an imminent one.
I was a high school senior, and I had the last class of the day as a "spare", meaning I could go home at 2:05pm every day.
One day in October, I didn't leave because I was looking for one of my friends. His phone had died, so I wandered around the halls for half an hour, checked the library, cafeteria, etc, then decided to go home.
Earlier in the day, a kid had his Mustang smashed up over some piddly shit, and, unbeknownst to me, the perpetrator (from another school) threatened to come back with a gun.
I went up to my locker, grabbed my stuff, put on my headphones, and started blasting Zeppelin and Hendrix on my trusty Micrsoft Zune (shoutout to /r/Zune, keep the dream alive, fellas). I, being a stupid teenager, had the volume on so loud I wouldn't hear an air raid siren going off next to my head. Man, those Zune brand headphones were good, I miss them.
While I'm playing around with my Zune, arranging stuff in my locker, looking at my calendar, the school recieves a tip from a Jr. High down the road that the aforementioned Muscle Car Vandal was spotted heading in our direction carrying a black duffle bag. CUE LOCKDOWN! GET SWAT OUT HERE NOW!
I'd later find out that a teacher had spotted me waking down the hallway while locking down, called "Hey kid! Hey blond kid! Hey!" but I didn't hear her and disappeared out of sight.
I go to walk out the front doors, oblivious to my surroundings, and find myself face-to-face with four police officers, guns drawn, forming a barricade with their cruisers.
They all turn, but as one near me turns around, he sweeps me with the barrel of his .40S&W Glock with his finger on the trigger, I drop my Zune, yanking my headphones out of my ears in the process, I shout "WHAT THE FUCK?!", they all start shouting "Get inside! Now!", I stumble around, pick up my Zune, he realizes what he's just done, yells "Sorry!" as I run back in, the Principal grabs me by the arm and drags me into his office to spend the next two hours hiding behind the receptionist's counter with the entire school administration. They wouldn't let me do anything, not even read. We tried playing word games, then realized it was inappropriate, so we sat there in silence.
Turned out it was the Ford Crusher indeed, but he'd just been going to hockey practice at the indoor rink next to our school. He was arrested and severely punished for what he'd done.
The cop apologized, but I wasn't mad, the principal jokingly ridiculed me for what happened after all was said and done.
My Zune was fine.