The mosque, the Salman Alfarisi Islamic Center, was an occasional place of worship for Mohamed Osman Mohamud, a 19-year-old Oregon State University student who attempted to set off a bomb in Pioneer Courthouse Square in Portland Friday, while the area was filled with people attending the city's annual Christmas tree-lighting ceremony.
The plot was foiled, Mohamud arrested and no one was injured in the attempt, authorities said.
The Corvallis fire was discovered at about 2:15 a.m. Sunday by an on-duty police officer. Firefighters contained the blaze to a single office in the two-story center. It destroyed about 80 percent of the office, including a chair and a computer. It also charred the pages of a Quran. No one was injured in the fire, authorities said.
Authorities concluded that the blaze was intentionally set, although they made no direct connection between the arson and the arrest of Mohamud on Friday. The FBI joined local authorities in the investigation and search for the arsonist.
The FBI is offering up to $10,000 for information leading to the identification, arrest and conviction of whoever started the fire.
"We have made it quite clear that the FBI will not tolerate any kind of retribution or attack on the Muslim community," said Arthur Balizan, Special Agent in Charge of the FBI in Oregon. "We are working very closely with the leadership at the mosque. We will find the person responsible for this attack and bring the full force of the federal justice system to bear."
On Saturday, before any attack on the mosque, the leaders of the Islamic center put out a statement condemning the alleged actions of Mohamud.
"We denounce this horrible plot in the strongest terms and repudiate all those who commit such acts of mindless violence in the name of Islam," the release said. "Islam is a religion of peace and these acts are not the legitimate acts of Muslims."
Federal authorities had been monitoring Mohamud, a Somali-born American citizen, for months prior to his attempt at terrorism and undercover agents had been working with him in developing the plot and devising the bomb.
"The device was in fact inert, and the public was never in danger," the government said in a release.
Mohamud parked a van containing the fake bomb at a corner of Pioneer Courthouse Square at 5:42 p.m. Friday, 18 minutes before the scheduled tree-lighting and while the square was filled with people awaiting the event. He then walked away and attempted to detonate the bomb via his cell phone. He was immediately arrested.
Mohamud is charged with attempting to use a weapon of mass destruction, and faces a maximum life sentence and a $250,000 fine, authorities said.
Mohamud is scheduled to appear in U.S. District Court in Portland today, authorities said.