Based on how the question is phrased, it can be very open to interpretation.

I've thought all kinds of sick thoughts along the lines of "I could push this person in front of the arriving metro", or "I'm holding a kitchen knife, if I were to stab the other person in the kitchen there's nothing they could do about it". When I was in the army, and we were at the shooting range, I could get thoughts about how easy it would be to shoot a whole load of people. Of course, I never consider doing those things. I'm talking about people I would lay down my life to protect, and I still get these thoughts.

I was very relieved when I read somewhere that this is fairly normal, and some researchers ascribed it to a protection mechanism: Their theory (which they provided some evidence for), was that be evoking these thoughts, your brain makes you more aware of acute potential dangers, so that you can act more carefully to avoid them. Basically, by becoming conscious that you could push/stab/shoot someone, you handle your movement/knife/firearm more carefully to avoid doing so by accident.

So: Have I thought about shooting someone? Plenty of times. Have I considered shooting someone? Never.