Where does the phrase ‘When the looting starts, the shooting starts’ come from?

WASHINGTON — Twitter said early Friday that a post by President Donald Trump about the protests overnight in Minneapolis glorified violence because of the historical context of his last line: “When the looting starts, the shooting starts.”

The phrase was used both by Miami’s police chief, Walter Headley, in 1967, and by presidential candidate and segregationist George Wallace the following year.

Hadley used it when he addressed his department’s “crackdown on … slum hoodlums,” according to a United Press International article from the time.

Headley, who was chief of police in Miami for 20 years, said that law enforcement was going after “young hoodlums, from 15 to 21, who have taken advantage of the civil rights campaign. … We don’t mind being accused of police brutality.”

https://www.nbcnews.com/politics/congress/where-does-phrase-when-looting-starts-shooting-starts-come-n1217676