When it heads downhill, it can happen fast. Here is a link to the dashcam video of Montana State Trooper David DeLaittre being killed during a traffic stop last December 1st.
The man who shot the officer was badly wounded in the exchange, but committed suicide rather than seek medical help.
David James DeLaittre was 23 years old. He was the youngest Montana Trooper ever killed in the line of duty.
The life of a man consists not in seeing visions and in dreaming dreams, but in active charity and in willing service.
–Henry Wadsworth Longfellow
Update: Edited to deal with a link change.