Sheriff Russ Isham of Marion County declined to release the suspect's name, saying it would jeopardize the integrity of the investigation and the safety of officers still working the case.

"We do believe the person responsible for the bombing is in custody," Deputy District Attorney Courtland Geyer said late Sunday.

The suspect was arrested in Salem, located just south of Woodburn, the small city south of Portland where Friday's bombing occurred.

Officers made the arrest shortly after Sheriff Russ Isham of Marion County released surveillance photos of a "person of interest." Geyer would not say if a tip led to the arrest.

He also wouldn't disclose if the man in the photos, apparently taken with a security camera, is the same person in custody.

Isham would not release the precise location where the arrest took place, and said the suspect's name likely wouldn't be released until Monday afternoon.

"I'm really proud of those who tirelessly worked to get us to this point and am humbled by the community's support," Isham said. "We know there is still a lot of hard work ahead of us, but this development will help bring relief to the local community and the officer's families."

The court issued a one-line denial of an appeal by contractors who worked at the Hanford nuclear reservation. The contractors — E.I. Du Pont De Nemours & Co., General Electric Co. and UNC Nuclear Industries Inc. — were challenging a lower-court ruling last spring that sided largely with the plaintiffs.

The people exposed to radiation lived in eastern Washington, eastern Oregon and Idaho, downwind of Hanford, as the U.S. government was developing atomic bombs in the 1940s.

The government did not disclose until 1986 that radiation had been released at the site, and since then the "downwinders" have sought compensation for thyroid cancer and other conditions they believe were caused by the exposure.

"This is very exciting for us," Richard Eymann, one of the plaintiffs' lawyers in the long-running case, told The Spokesman-Review of Spokane. "With a new administration coming in, we want a serious look at compensation for these people after years of litigation."

So far, the plaintiffs have not agreed to a settlement offer by the contractors that would compensate them based on the amount of radiation they likely received and the illnesses they have, said Kevin Van Wart, lead attorney in Chicago for the Hanford contractors.