An aircraft violated the restricted airspace around federal Washington on Wednesday, prompting security officials to raise the threat level from yellow to orange and order personnel in the U.S. Capitol to prepare to evacuate.

Capitol Police Sgt. Kimberly Schneider said the plane was diverted to a landing in northern Virginia, where the pilot was being interviewed.

Michael Kucharek, a spokesman with North American Aerospace Defense Command, or NORAD, said two F-16s were scrambled about 10:15 a.m. after a plane heading south from Maryland violated the restricted airspace.

The military agency also used a laser system that visually warns pilots they are in a restricted area, Kucharek said. The pilot turned west and landed at an airport in Leesburg, Va., while under escort from the fighter jets.

It wasn't immediately clear how close the plane had come to the Capitol building, where the U.S. Congress sits.

The Capitol was not evacuated, but tourists were turned away for a time. The threat level was soon returned to yellow, or elevated and later, green — or low threat — according to police and other officials.

White House press secretary Dana Perino said the White House was notified.

"There was an aircraft that entered into the airspace that there was some concern about, but the aircraft turned around," she said. "We are at normal security levels here at the White House."