Here’s how a news outlet addresses mistaken reporting:

WASHINGTON (AP) — In some stories that moved Sept. 16 and Sept. 17 about the shootings at the Washington Navy Yard, The Associated Press erroneously reported that the gunman, Aaron Alexis, carried an AR-15. That information was based on federal law enforcement officials who were relying on initial descriptions from the scene and was included in official internal FBI reports summarizing the shooting. However, additional investigation by law enforcement concluded that Alexis carried a shotgun, took at least one handgun from an officer at the scene but did not have or use an AR-15.

Erik Wemple writes the Erik Wemple blog, where he reports and opines on media organizations of all sorts.