A pilot and student pilot, en route from Pennsylvania to an air show in North Carolina, were taken into custody after their flight sparked a frenzy of activity that tested the capital's post-Sept. 11 response system.

The government decided not to press charges after interviewing the men and determining the incident was an accident. "They were navigating by sight and were lost," said Justice Department spokesman Kevin Madden.

Officials had been concerned because the plane appeared to be "on a straight-in shot toward the center of the Washington area," said Capitol Police Chief Terrance W. Gainer.

The White House raised its threat level to red - the highest - for eight minutes, said spokesman Scott McClellan. Vice President Dick Cheney, first lady Laura Bush and former first lady Nancy Reagan, overnighting at the White House for a special event, were moved to secure locations.

President Bush, biking with a high school friend at the Patuxent Wildlife Research Center in Beltsville, Md., was unaware of the midday, 15-minute scare as it was occurring.

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.

A guard at the White House told reporters who hadn't already left to "go down into the basement area."

At the Supreme Court, guards told some people to leave the building while others were shepherded into the underground parking garage, where Justices John Paul Stevens, Sandra Day O'Connor and Stephen Breyer were seen chatting. At Treasury, an announcement on the loudspeaker advised employees to move to a shelter.

The Defense and State departments were exceptions, with neither evacuated. Defense Secretary Donald H. Rumsfeld remained at the Pentagon, where many were killed when terrorists crashed an airliner on Sept. 11, 2001. Secretary of State Condoleezza Rice conducted a television interview unaware of the plane.

The incident began at 11:28 a.m., when Federal Aviation Administration radar picked up the aircraft, a small two-seater Cessna 152 with high wings. Gainer said the first alert went out when the plane was 21 miles - 17 minutes - from the city.

Two Black Hawk helicopters were dispatched at 11:55 a.m. from Reagan National Airport. Two F-16 jet fighters, scrambled from Andrews Air Force Base, fired four warning flares when the Cessna's pilot did not respond to radio calls.

"If he wouldn't have responded, intentionally or not, he could have been shot down," said Master Sgt. John Tomassi of the North American Aerospace Defense Command in Colorado Springs, Colo.

The plane then turned to the west and the warplanes escorted it to the airport in Frederick, Md., where the men aboard were taken into custody and questioned by Secret Service, FBI and local authorities.

The plane was registered to Vintage Aero Club, a group of people who fly from Smoketown Airport in Pennsylvania's Lancaster County, said club member Merv King. Former club member John E. Henderson said the plane was to be flown by Jim Sheaffer of Lititz, Pa., and student pilot Troy Martin, of Akron, Pa., to an air show in Lumberton, N.C.

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."

Washington's Reagan National Airport has been closed to general aviation, the non-airline planes, since the Sept. 11 terrorist attacks. In the 3 1/2 years since then, hundreds of small planes have flown within the restricted airspace around the capital - a 15 3/4-mile radius around the Washington Monument.

However, it's rare for fighter jets to be scrambled in response.

In the most dramatic previous incident, thousands of people fled the Capitol, packed with members of Congress and other dignitaries, when a plane flew into the restricted airspace just before the funeral procession for President Reagan last June.

A communications breakdown led federal officials to believe the plane might be targeting the Capitol, but it turned out to be carrying Kentucky Gov. Ernie Fletcher, who had been cleared to fly into the area.

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Associated Press Writers Mark Scoloforo in Harrisburg, Pa., and Erin Gartner in Denver contributed to this report.

© 2005 The Associated Press