Washington ? A small plane strayed within three miles of the White House on Wednesday, leading to frantic evacuation of the Executive Mansion and the Capitol with military jets scrambling to intercept the aircraft and firing flares to steer it away.

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. His security detail knew of the raised threat level.

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.

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 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.

A Maryland State Police Trooper kneels over one of two people who were detained Wednesday at the Frederick, Md., Municipal Airport after flying in restricted airspace over Washington. The plane was forced to land at the airport by U.S. Air Force fighter jets and a U.S. Customs Blackhawk helicopter. The Frederick airport is about 50 miles from Washington.

One Black Hawk helicopter and one Citation jet were dispatched at 11:47 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 men were identified as Hayden Sheaffer, of Lititz, Pa., and Troy Martin, of Akron, Pa., according to a federal law enforcement official who spoke on condition of anonymity.