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.

A teenager in Oregon planned to set off an explosive at a shopping mall in Washington state and shoot people as they fled the movie theater there, said law enforcement officials, one of whom said the plot "was as serious as it gets.

The FBI thwarted an improvised explosive attack and a potential mass shooting that was intended to take place at Three Rivers Mall in Kelso last month.