A regional joint terrorism task force coordinated a series of arrests in the two states, Ashcroft said at a Justice Department news conference.
Two other fugitives outside the U.S. were also charged in an indictment returned in Oregon by a federal grand jury.
Five of the six suspects are U.S. citizens, and one had U.S. military training, the attorney general said. Court records unsealed Friday said all six suspects had traveled to Afghanistan for training.
Court papers identified the six as former Army reservist Jeffrey Leon Battle, Patrice Lumumba Ford, Ahmed Ibrahim Bilal, Muhammad Ibrahim Bilal, Habis Abdullah al Saoub and October Martinique Lewis, the ex-wife of Battle.
Friday's arrests, Ashcroft said, represent "a textbook example" of cooperation among federal, state and local authorities in the war against terrorism.
But, as CBS News Correspondent James Stewart reports, the latest arrests are what appear to be terrorist wannabes as opposed to full-fledged al Qaeda members.
Ashcroft said the cell began forming plans to go to Afghanistan and help al Qaeda not long after the Sept. 11 attacks.
Says Ashcroft, "The indictment charges that the five defendants purchased airline tickets to Hong Kong with the intent of traveling to Taliban controlled Afghanistan via China and Pakistan."
Their goal was to join forces with al Qaeda and the Taliban and fight against the U.S, but their timing was off. The cell members began buying airline tickets for the long trip the same week the U.S. began its bombing campaign in Afghanistan.
The result was a frustrating journey. The men left Portland and flew to Hong Kong before traveling to Beijing. Unable to cross the border there, they tried to gain entry through both Indonesia and Bangladesh before most finally gave up and returned to Portland.
U.S. officials wouldn't guess as to the motive and say there's no indication any of the four suspects in custody ever succeeded in making contact with al Qaeda. Also, like the six Buffalo area men recently charged with aiding al Qaeda, officials say they can find no evidence the Portland cell had picked a target or had any ongoing terrorist plans.
Several of the suspects reportedly lived in a Portland apartment complex and investigators say they were first tipped off to the cell when they began training with shotguns and small arms at a quarry.
Skamania County Sheriff Charles Bryan tells Stewart, "It started as a routine call. A neighbor had heard the noise of gunfire. A deputy was dispatched, by himself (he) then encountered these individuals."
What is striking about these arrests is the same thing that stuck out in the Buffalo case: once again the suspects aren't foreign born agents, but homegrown Americans.
As CBS News Correspondent Bill Whitaker reports, the investigation continues in Oregon after arrests were made. At dawn, 100 agents with arrest warrants swarmed a south Portland apartment complex picking up Battle and his ex-wife Lewis. Ford was arrested elsewhere and all the police activity surprised neighbors.
One neighbor says, "The last thing I'm worried about is whether I have terrorists living in my house or my neighborhood."
Surprise, too, at the Riswan mosque a block away, where the mosque president says he never heard of these people.
Mizra Lugman told Whitaker, "Absolutely not. Nobody from these apartments come to this mosque."
Investigators have been looking for -- and they say finding -- terror connections in Oregon for months now.
For instance, James Ujaama is facing trial in Washington for allegedly trying to set up an al Qaeda training camp in Bly, Oregon.
An unindicted co-conspirator in the Portland case is U.S. citizen Ali Khaled Steitiye. He was sentenced to prison in Portland two weeks ago on unrelated gun and immigration charges. The leader of his mosque, Sheik Mohamed Kariye, goes on trial next month in Portland on social security fraud charges. Officials say the joint task force may not be done yet in Oregon.
Charles Mathews of the FBI says, "The investigation is continuing ... here at Portland pertaining to other individuals who also may have traveled to Oregon after September 11."
Meanwhile, noting the sentencing in federal court Friday of John Walker Lindh and the guilty plea in Boston from accused shoe-bomber Richard Reid, Ashcroft called it a "defining day" in the fight against terrorism.
FBI Director Robert Mueller told reporters that "those who support terrorism or acts of terrorism will be brought to justice."
Ashcroft said some of the suspects began traveling to Afghanistan in October 2001 to fight with Taliban troops against U.S. forces.
The suspects face charges of conspiracy to levy war against the United States, conspiracy to provide material support and resources to al Qaeda, conspiracy to contribute services to al Qaeda and the Taliban and possessing firearms in furtherance of crimes of violence.
The indictment said they engaged in weapons training in Washougal, Wash., starting in late September 2001, to prepare to fight with Taliban forces. Some of the men sent money to others overseas to support their efforts, the court documents charged.
Battle obtained an administrative discharge from the U.S. Army Reserve in January 2002. The indictment said Battle had enlisted to receive training in U.S. tactics and weapons, which Battle ultimately intended to use against American soldiers.