That was because of Waterloo in 1994.
A Walmart security officer approached a man who had brazenly stolen a big screen tv. He asked him to come back to the store and the man pulled out a gun and shot the security officer point blank.
https://www.freerepublic.com/focus/news/3769053/posts
At Least 9 Dead, 16 Injured In Mass Shooting In Downtown Dayton, Ohio: Police