WASHINGTON — Two lost aviators flying with outdated maps from a rural Pennsylvania airstrip yesterday triggered a red alert and the frantic evacuation of the White House, the Capitol and the Supreme Court before they were intercepted by Air Force jets firing warning flares.

The 15-minute aerial encounter, watched by rapt workers in downtown Washington office buildings, turned out to be a blunder by confused fliers in a small plane, but it illustrated how easily potential danger can trip the capital's tightly wired alert systems.

As the aircraft bore down on Washington from the north and officials could not contact the pilot, the White House's internal threat level went from yellow, to orange and then to red within four minutes; fighters were scrambled; and occupants and visitors at the White House, the Capitol, the Supreme Court and congressional office buildings were sent scurrying for safety.

The aircraft flew over the vice president's residence, a senior federal security official said, came within moments of reaching the White House and was close to being shot down.

At the Capitol, lawmakers, tourists and reporters raced out of the building, dodging the speeding motorcades of Latin American leaders who had been meeting with members of Congress. House Speaker Dennis Hastert, R-Ill., was hustled to a secure location. Police, rushing to get House Minority Leader Nancy Pelosi out of the building, lifted her out of her shoes.

Armed security officers raced through the Capitol shouting for people to leave. "This is not a drill!" some yelled as they moved people away from the building. "There's a plane coming," warned another.

"It was relatively orderly," said one Senate worker who fled the Capitol. "But there's still panic, there's always panic. You start to run faster than you think you can run."

Officials said 35,000 people were evacuated from the Capitol and adjacent office complexes. An additional 200 were evacuated from the White House.

First lady Laura Bush and former first lady Nancy Reagan, who was visiting, were ushered to a bunker beneath the White House for safety, and Vice President Dick Cheney was taken to a secure location, officials said. The president, who was riding his bicycle at the Patuxent Wildlife Research Center in suburban Maryland, was alerted by his security detail after the drama was over.

The two aviators were identified as Hayden Sheaffer, 69, of Lititz, Pa., and Troy Martin, 36, of Akron, Pa. They were released without charges after authorities determined they posed no security threat.

Sheaffer confirmed he had been released by authorities but declined to comment further when reached on his cellphone by The Associated Press.

White House spokesman Scott McClellan said the government has specific rules on when an intruding civilian aircraft can be shot down. Pentagon officials said Defense Secretary Donald Rumsfeld was contacted and available to execute a shoot-down order if necessary.

"This guy probably came as close as he could come without getting shot out of the air," Capitol Police Chief Terrance Gainer said.

Authorities said the plane's occupants were so clueless that when officials finally made radio contact and ordered the plane to divert, the fliers refused, asserting their right to proceed on their way.

It was only when the F-16s fired four bright flares across the plane's nose that the two men realized the gravity of their situation, officials said. The plane then veered northwest, out of town, escorted by the interceptors, security helicopters and a U.S. Customs jet.

The aircraft, an old-fashioned white Cessna 150 that weighs about 1,000 pounds and has a top speed of 160 mph, was directed to the Frederick, Md., airport, where the men were detained for questioning.

In Pennsylvania, relatives and neighbors expressed shock that Sheaffer and Martin had wound up in so much trouble while on a flight to an air show in Lumberton, N.C. Martin, who neighbors said was learning to fly, was at the controls, according to investigators; Sheaffer, who according to his sister is a seasoned pilot, was in the passenger seat.

Martin's wife, Jill, said: "Troy was discussing with me last night after they made their flight plans all about the no-fly zones and how they were going to avoid them. He said they were going to fly between two different restricted areas."

But authorities said the men probably erred because they were using old navigation maps.

"They were lost and had no idea where the hell they were," said one federal law-enforcement source close to the investigation. "They were confused and scared."

Lenny Harding, a neighbor and friend of Martin's, called the incident over the skies of Washington "a mistake, an honest mistake, a big honest mistake."

But Phil Boyer, president of the Frederick-based Aircraft Owners and Pilots Association, a 400,000-member pilot education and lobbying group — of which he said Martin is a member — said there "was no excuse" for the mistake.

"We send hundreds of e-mails and messages a year giving pilots instructions on how to fly here," Boyer said. The likely penalty for a pilot who strays into restricted airspace is license suspension for 30 to 120 days, he said.

Material from The Associated Press is included in this report.