KAHULUI, Maui — Passengers arriving at Kahului Airport last night aboard Hawaiian Airlines Flight 39 said there was no commotion or any other sign of trouble aboard the plane before it turned back to Portland because of what officials described as "a suspicious passenger."

The captain of the Boeing 767 jet made a decision to return to Portland International Airport about 90 minutes into the seven-hour flight when an uncooperative passenger made threatening remarks and refused to store his carry-on bag, according to the Transportation Security Administration.

Two F-15 fighter jets from the Oregon National Guard escorted the Hawaiian flight back to Portland as a precaution.

A 56-year-old Salem, Ore., man and his female companion, along with their luggage, were removed from the flight but were later released, FBI officials said. There is no known terrorism link to the incident and the case was turned over to federal prosecutors for possible criminal charges, the FBI said.

The incident comes amid heightened concern about airline security and the charge that a Nigerian man tried to blow up a a Detroit-bound Northwest Airlines jetliner on Christmas Day.

Kahului hotel worker Randy Monje, 49, was among the 231 passengers on Hawaiian Flight 39. He said he was sitting a couple of rows behind the couple who were taken away, and that passengers initially were told the plane was turning around because of a mechanical problem.

"By the time the plane was going down to land, you could see a lot of fire engines, and by the time the plane stopped on the tarmac, that was when the police came on," Monje said.

He said he didn't observe any unusual behavior by the passenger or his companion, who was wearing a neck brace, and that they didn't make a fuss when they were removed from the plane in Portland.

The remaining passengers were told to stay in their seats while airline gate staff came aboard to search the lavatories and overhead storage bins, Monje said. After about an hour, the plane took off for Maui for a second time.

Craig Wasley, 38, of Spokane, Wash., said the most unnerving part of the experience was worrying about a possible crash landing, especially when the flight experienced turbulence as it neared Portland.

"We were told there were mechanical problems. We didn't know at the time that there were fighter planes around us," said Wasley, who is celebrating his fifth wedding anniversary on Maui with wife Sharon.

"When we landed, we were able to see the emergency vehicles on the landing strip with their flashing red lights like they were preparing for the worst."

Wasley, who owns a construction company, said he never considered whether a terrorist might be on board "because there was no suspicious activity going on. It seemed like it was business as usual.

"I think they handled it quite well. I never felt at any point like things were out of control."

TSA spokeswoman Suzanne Trevino said the Hawaiian Airlines captain decided to return the plane to Portland "due to a suspicious passenger who made threatening remarks and refused to store his carry-on bags."

Authorities provided no details about the threats made by the Salem man or the issue with his baggage.

The Hawaiian flight first departed Portland at 8:10 a.m. Hawai'i time, said airline spokesman Keoni Wagner, and about 90 minutes later the plane turned around, landing in Portland at 11:23 a.m.

"The crew elected as a precaution to turn around and bring the person back to Portland," Wagner said.

The North American Aerospace Defense Command spokesman John Cornelio said the agency didn't know what kind of disruption the Hawaiian flight crew was dealing with, so two F-15 fighters from the 142nd Fighter Wing were scrambled as a precaution.

"Based on the information we had, we decided it was prudent to launch," he said.

He said the decision was made by NORAD, not by the Federal Aviation Administration.

Wagner said the airline was "surprised" by the response.

"We think that was an overreaction," he said. "We did not request fighter escort."

After refueling at the Portland airport, Flight 39 took off for Maui a second time at 12:40 p.m. Hawai'i time, arriving in Kahului at 7:30 p.m.

KATU News in Portland reported that a least three passengers who were upset by the incident decided to disembark from the plane when it returned to Portland after turning around.