Passage: Capone was born in New York City, to Italian immigrants. He was a Five Points Gang member who became a bouncer in organized crime premises such as brothels. In his early twenties, he moved to Chicago and became a bodyguard and trusted factotum for Johnny Torrio, head of a criminal syndicate that illegally supplied alcohol—the forerunner of the Outfit—and was politically protected through the Unione Siciliana. A conflict with the North Side Gang was instrumental in Capone's rise and fall. Torrio went into retirement after North Side gunmen almost killed him, handing control to Capone. Capone expanded the bootlegging business through increasingly violent means, but his mutually profitable relationships with mayor William Hale Thompson and the city's police meant he seemed safe from law enforcement.

Question: Why did Torrio go into retirement?
North Side gunmen almost killed him