A 19-year-old Somali-American will appear in court in Portland, Oregon, Monday for attempting to set off a car bomb near a large crowd at Portland's Pioneer Courthouse Square.
Mohamed Osman Mohamed, charged with the "attempted use of a weapon of mass destruction," was arrested Friday after trying to set off what he thought was an explosives-laden van parked near the tree ceremony in Portland's Pioneer Courthouse Square.
The device, however, was a fake supplied by undercover agents from the FBI who had contacted Mohamed months before, pretending to be accomplices in the plot.
"The threat was very real. Our investigation shows that Mohamed was absolutely committed to carrying out an attack on a very grand scale," said FBI special agent Arthur Balizan to AP.
On Sunday, an Islamic centre was set on fire two days after Mohamed was caught in a federal sting operation, trying to blow up a van full of explosives during a Christmas tree lighting ceremony.
Police in Corvallis, Oregon said that the fire at the Salman Al-Farisi Islamic Centre was started intentionally after finding incriminating evidence at the scene.
"We eliminated other causes of the fire, and we do have evidence that it was arson," Carla Pusateri of Corvallis' Fire Department said on Sunday.
Though no one was injured in the incident, the blaze gutted one room of the Salman Alfarisi Islamic Center, the BBC reports.
The fire burned 80 per cent of the centre's office but did not spread to worship areas or any other rooms, said Yosof Wanly, the centre's imam.
Authorities don't know who started the blaze or why, but they believe the centre was targeted because Mohamud occasionally worshipped there.
The FBI was working closely with leadership at the Corvallis centre as agents investigated the fire.