Lady hit by falling bullet in Denver.

[FoxtArt]

" A bullet fired straight up, with no wind, might reach a height of 10,000 feet (about three kilometers), but will come back down at only around 150 miles per hour: just 10% of the speed and with only 1% of the energy as the originally fired bullet." --- https://www.forbes.com/sites/startsw.../#6c821cbc3d22

That mean a 9mm fired into the air that has a muzzle energy of 350-400 ft/lbs would only be 3.5 to 4 lf lbs of energy. Less energy than someone dropping a soda on your foot from waist high.

Most bullets aren't fired perfectly straight up though, where their original velocity is terminated. If they aren't fired perfectly vertically, they still retain enough kinetic energy to pierce a body even after apogee - even a couple miles away, or more.

ETA: I've seen studies on perfectly vertical firings of 30-06, and they did significantly dent boards. They might even have enough energy to go through a shoe and draw blood. 9mm, who knows. We can't draw general conclusions even on a vertical firing from the term "bullet" because they will all have a vastly different drag coefficient backwards (they maintain their gyroscopic spin and point of aim, even as they fall back down). Some bullets might have a much, much higher terminal velocity - like ones that have a tapered base. E.g. comparing a 30-06 to a 45 to a 9mm to a 50bmg even on a perfectly vertical firing, I'd bet at least one of those, probably more, could still kill a person.