I'd encourage you to watch the entire list of videos to get a sense for what policing is like in parts of America, and what circumstances lead to the use of deadly force. Some of them are difficult to watch, but it showcases both good and bad examples of how to handle extremely dangerous situations.
It's not an enviable job - the number of videos that start out as a routine traffic stop with the cop having amiable conversation, and then rapidly escalate to a situation where the suspect is pulling a gun on the officer, is truly mind-blowing.