We need to use caution when interacting with those who are sworn to "protect and serve".
We have completely "lost the bubble" on this one. Police officers are not better citizens, nor are they justified in violating other citizen's rights simply on the slight possibility that an old guy is reaching for a rifle instead of his cane. The cop in question had many other options available but chose to fire multiple shots instead of all the other potential options (such as taking cover, moving forward to seize the "weapon" if he/she was close enough, etc.).
This kind of atrocity needs to be stopped and the police who perpetrate it charged with a crime. If this can't be done, our Constitution means nothing.