When you fire a gunshot straight up into the air, it can go up as high as 3 kms (depending upon the weapon, the size of the bullet, and a few other factors).
After it has reached its highest point, it must come down because of gravity.
When it is falling down freely, the air provides resistance and the speed is reduced to about 10% of the speed with which it was shot.
But in a lot of cases, this 10% can also prove to be quite dangerous.
For example, AK-47 is estimated to fire bullets that travel at a speed of 2300 feet/second & 10% of this speed would be 230 feet/second.
Research suggests that a speed of 200 feet/second is enough to penetrate the skull.
Free-falling bullets from the guns which fire at lower speeds (1800 feet/second or less) are unlikely to kill anyone unless it is a direct hit to the eye, ear, or mouth.
This is true, however, only if the shot is fired straight up (at 90 degrees angle from the ground).
At 45 degrees or less, even slower gunshots can be lethal, because they will fall at much higher speeds than 10% of the straight-up speed.
A number of incidents have been recorded of people dying or getting badly injured because of randomly falling bullets.
One of the most notable incidents happened when a Democratic member of the Texas House of Representatives Armando Martinez was hit by a stray bullet in 2017.
A fragment penetrated the top of his skull and had to be removed through surgery.
