they are metal bullets coated with a thin layer of rubber. the cops obviously know this. they aren’t non lethal. they are not meant for close range.
they were invented as a way to break up riots by firing the bullet at the ground with the intent to bounce into people’s legs without much injury and are expected to produce contusions, abrasions, and hematomas in those cases but they can kill.
police that are shooting them point blank at people's heads are shooting to kill.