CORVALLIS, Ore. – Someone set fire to an Islamic center Sunday, two days after a man who worshipped there was accused of trying to blow up a van full of explosives during Portland’s Christmas tree lighting ceremony. Other Muslims fear it could be the first volley of misplaced retribution.

The charges against Mohamed Osman Mohamud, a Somali-born 19-year-old who was caught in a federal sting operation, are testing tolerance in a state that has been largely accepting of Muslims. Muslims who know the suspect say they are shocked by the allegations against him and that he had given them no hint of falling into radicalism.

The fire at the Salman Alfarisi Islamic Center in Corvallis was reported at 2:15 a.m., and evidence at the scene led authorities believe it was set intentionally, said Carla Pusateri, a fire prevention officer for the Corvallis Fire Department.

Authorities don’t know who started the blaze or exactly why, but they believe the center was targeted because Mohamud occasionally worshipped there.

Mohamud was being held on charges of plotting to carry out a terror attack Friday on a crowd of thousands at Portland’s Pioneer Courthouse Square. He is scheduled to appear in court today.

On Friday, he parked what he thought was a bomb-laden van near the ceremony and then went to a nearby train station, where he dialed a cell phone that he believed would detonate the vehicle, federal authorities said.

Instead, federal authorities moved in and arrested him. No one was hurt.

There were also no injuries in Sunday’s fire, which burned 80 percent of the center’s office but did not spread to worship areas or any other rooms, said Yosof Wanly, the center’s imam.

After daybreak, members gathered at the center, where a broken window had been boarded up.

“I’ve prayed for my family and friends, because obviously if someone was deliberate enough to do this, what’s to stop them from coming to our homes and our schools?” said Mohamed Alyagouri, a 31-year-old father of two who worships at the center. “I’m afraid for my children getting harassed from their teachers, maybe from their friends.”

Wanly said he was thinking about temporarily relocating his family because of the possibility of hate crimes.

“We know how it is, we know some people due to ignorance are going to perceive of these things and hold most Muslims accountable,” Wanly said. “We do what we can, but it’s a tough situation.”