The U.S and it's security system.

As we know in Baltimore, Maryland there have been riots claiming for justice due to the "homicide" of Freddie Gray by 6 police officers. This is not the only case we know about unfair treatment of police man against residents like for example when Walter Lamer Scott was shot by a police officer after he had already hit him with a stun gun, or the  Mexican man who was also killed by police officers in Pasco, Washington.
Most of us see this kind of news and get scared, angry and start to lose the trust we are suppose to have in our police officers. There have been a lot more offenses committed by officers against civilians that make us all question their use of force and how secure we are. As we all know we have officers because we need to make sure everyone follows the rule and of course to protect us all but what is gong on now a days? Their actions seem to show that they don't care about doing their job right like it happen with Freddie as it is said in the article " The Timeline of Freddie Gray's Arrest and the Charges Filed" on The New York Times, "Officer Goodson stopped the van .... and went back to observe Mr. Gray.  'Despite stopping for the purpose of checking on Mr Gray's condition, at no point did he seek nor did he render any medical assistance for Mr Gray,' Ms Mosby said." Because of the police indifference about Mr. Gray he ended up dying of the injuries he suffered and was not attended for in the van. Many believe that if the people of Baltimore had not done the riots no one would have filed charges against the officers and that peace has lost its credibility.
From my point of view I see the officers decisions as inappropriate or dumb. They clearly don't seem to know what they are doing, as if they hadn't been trained for the job they are assigned to do, I see many other decisions they could have taken before going with the one of taking someone's life away, many people seem to think like this because it is true, they are trained to deal with this type of cases and lately it seems like they have forgotten and don't care but recalling a "parent meeting" I attended with my parents about a week ago where they brought in an officer to answer our questions the officer presented said that because of the recent incidents happening with the police and people they are sending their staff into more training to be thought how to handle a similar situation. This to me made me wonder if this is something that needs to be enforced all around the country to change the situation.
I wonder if there is a bigger  reason I don't see of why officers seem to be acting irresponsibly against civilians when they are suppose to protect us and enforce the law but not to a degree of killing people. I do not know what being a police officer fully implies but I do know that it is a big major job that you have to be trained for and that needs every ounce of you to do it right to be able to protect civilians and carry out the law at the same time. It just seems like The U.S is loosing control of the security for the nation and the people.