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.

The FBI derailed a plot by a teenager who had planned to detonate a bomb at a Washington state shopping mall and shoot people as they fled a movie theater in the building, law enforcement authorities announced Thursday.

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.