I recommend that you listen to the story and not just read it. You will hear the emotions of the people, now in their late 60s and 70s. This shooting incident has been multiplied many times over in the years since. The victims' families and survivors have the scars from each of these events. There are the physical scars that have healed and the physiological ones that will likely never heal. Imagine the impacts from all the shootings since that time.
NBC News noted that the anniversary coincided with the date that students at universities in Texas can legally carry a concealed weapon. There are multiple concerns about that happening. I keep thinking about the student engaging a shooter and the police not knowing that "the person with a gun shooting" is a good guy and not the perpetrator. It might be a good way to be shot by police.