“Babel” (2006)
https://www.imdb.com/title/tt0449467/
Detailed plot summary on Wikipedia here:
https://en.wikipedia.org/wiki/Babel_(film)
Quote from the above Wikipedia page:
“Doubtful of the rifle‘s purported three-kilometer range, they decide to test it out, aiming first at rocks, a moving car on a highway below, and then at a bus carrying Western tourists.”
I am pretty sure that this is the movie you are looking for. If you agree, then please select my answer as Best Answer by clicking on the “Select” button.
casspir Edited answer Feb 12, 2021