Like most of us that had to carry on as usual that day as best we could after watching the towers fall as we were waking up, I had classes at a university right next to Hill Air Force Base in Utah. Seeing and especially hearing F-16s overhead in that area was not unusual, it was/is a fully active base so training runs and flights were routine with little to no ordnance.
At this point all commercial aircraft had been grounded so that made it slightly eerie. I parked and began walking to my first class and things were not routine. I immediately heard and then saw a pair of F-16s flying faster and lower than I had ever experienced and each was loaded with enough ordnance to conquer a small nation.
At the same time I felt great fear but also great pride because this time they were hunting with purpose and I almost felt sympathy for any enemy they might find, knowing they would be overwhelmingly ended.
I will never forget.