A little late to the party, but here's my 'dramatic, scary' story:
I used to work for a religious institution that had it's share of death threats sent to the big bosses. So, security was very important. We were in a donated building that was cornered on three sides by an interstate, conservation land, and a giant cemetery. I was the help desk manager and walked around the building a lot, taking tech issues and resolving them.
This particular day, I was sent over to a lady in finance, who had a desk next to the window on the third floor. She was on the telephone. I waited, off to the side looking at the pretty snowscape out the window in the conservation land. Then, I noticed movement.
What I thought I saw was a man up a deer blind with a rifle. Eeek!!!!! He was either aiming at conservation land, the interstate or us.
I turned and ran down the stair as fast as I could. Our head of security (Fred) was a retired state trooper and took his job VERY seriously. I bolted to his desk in the mailroom and told him what I thought I had seen. His assistant mentioned 'the strange van was back in the parking lot'. The security head took off and his assistant and I headed to the window.
The potential hunter was entering our lot! Fred confronted him. We couldn't see anything else. Fred eventually re-entered the building. I was slightly off in my observation. It was not a rifle. It was a machete!
It turns out the machete man was an employee of the highway department. He built the blind to see progress on a road construction project and was parking in our lot, since it was the only one around. My powers of observation made me one of Fred's most popular employees - while I was wrong, I did still spot a stranger near the building with a weapon, even if it was a completely legitimate situation.
I've also run into the SWAT team at an apartment complex, slept through a nearby fatal car accident in which the vehicle rolled three time before catching fire about 65 yards from my bedroom window, and had to keep my 11 pound rat terrier, which is derived from smooth coat fox terriers, from a mangy fox that liked to sunbathe about a block from our apartment. Morty, the terrier, became Scrappy Doo whenever he could smell that fox and I think the fox liked to taunt him.