An Oregon teen has been arrested in connection with an alleged mass shooting plot targeting the Three Rivers Mall in Kelso, in southwestern Washington, officials said. The suspect, whose identity has not been disclosed due to his age,

The plot, described by one official as being “as serious as it gets,” involved a plan to shoot moviegoers at a Washington State mall as they fled an explosion.

The FBI thwarted a potential mass shooting by a teenager who planned to set off an explosive at a shopping mall in Washington state and shoot people as they fled the movie theater there, law enforcement leaders said Thursday.