Update at 6:38 p.m. ET: In a news release, the U.S. Attorney calls it an "improvised explosive device," or IED, the common term for bombs used against U.S. troops in Iraq and Afghanistan.

If convicted on the charge of attempted use of a weapon of mass destruction, Harpham could be sent to prison for life. The other charge, possession of an unregistered explosive device, carries a maximum prison term of 10 years.

Though federal officials have previously called the attempted bombing an act of domestic terrorism, there was no explanation for why Harpham was not charged with terrorism or related crimes.

Update at 6:31 p.m. ET: Here's what Attorney General Eric Holder had to say this afternoon at a press conference unrelated to the bombing case: "I can say that it was a viable device, it was planted with the aim of injuring or killing people and we were fortunate that it did not go off and that people were in fact not killed. We were just lucky in that regard."

Update at 4:41 p.m. ET: Kevin William Harpham is to appear in federal court later this afternoon, The Spokesman-Review now reports, citing court documents. He is being charged with attempted use of a weapon of mass destruction and possession of an unregistered explosive device.

Update at 3:53 p.m. ET: The Spokesman-Review, citing a source, is identifying the suspect as 36-year-old Kevin Harpham, a U.S. Army veteran and white supremacist originally from Kettle Falls, Wash. ("1610 Friendly People & One Grouch")

The Southern Poverty Law Center says that in 2004 Harpham was a member of the National Alliance, which it describes as one of the most visible white supremacist organizations in the nation. The group was founded by the late William Pierce, who wrote The Turner Diaries, a novel about a future race war that is believed to have influenced Oklahoma City bomber Timothy McVeigh.

Records show Harpham served in 1996 and 1997 with the 37th Field Artillery Regiment at Fort Lewis, Wash., according to Mark Potok, head of the Southern Poverty Law Center.

Update at 3:15 p.m. ET: U.S. Attorney Mike Ormsby said his office is preparing a news release that will identify the suspect, The Spokesman-Review says. But he cautioned that few other details would be revealed.

A neighbor told KHQ-TV the man was apprehended as he drove across a bridge over the Colville River in northeastern Washington. Agents used explosives to open a door at a residence in Addy, south of Colville. The neighbor described the home as a trailer.

Authorities have described the bombing attempt as domestic terrorism.

By Doug Stanglin

USA TODAY

Update at 2:19 p.m. ET: KHQ-TV reporter Anthony Gomes reports that FBI vehicles have converged on a home south of Colville, Wash., in Stevens County and are serving a search warrant.

Earlier posting: Federal officials say a suspect has been arrested in the case of a bomb found at a Martin Luther King Day parade in Spokane, Wash., the Associated Press reports.

The Spokesman-Review reports that dozens of FBI agents from across the Northwest had begun assembling in Spokane earlier this week because of an expected breakthrough in the case.

The bomb was found along the MLK parade route on Jan. 17, just minutes before the event was going to get underway.

The explosive device was found in a backpack and the march was re-routed.

The Spokesman-Review says unidentified sources described the device as sophisticated and capable of being detonated remotely.