Official: FBI tipped off
Washington - A law enforcement official says federal agents began investigating the suspect in the Christmas tree bombing plot in Oregon after receiving a tip from someone who was concerned about the teenager.
The official tells The Associated Press that Mohamed Osman Mohamud was acting on his own - without any instruction from a foreign terrorist organisation.
The official was not authorised to discuss the investigation publicly and spoke on condition of anonymity.
The official said on Saturday that Mohamud hatched the plan on his own to use a cell phone to detonate what he believed was an explosive-filled van at a crowded Christmas tree lighting ceremony on Friday.
The official said Mohamud alone planned the details, including where to park the van for the maximum number of casualties.