ALEXANDRIA, VA — APRIL 20: Streaks of light from planes taking off are shown in this long exposure photograph of the control tower at Reagan National Airport on April 20, 2011 in Alexandria, VA. (Photo by Ricky Carioti/The Washington Post)

An evacuation at a Federal Aviation Administration air traffic control center in Leesburg, Va. delayed hundreds of flights around the region Monday night, authorities said.

The Metropolitan Washington Airports Authority said there were ground stops at all three major airports in the region, meaning inbound flights didn’t take off from their origins for hours. Delays for departing planes were averaging at least 90 minutes at each airport, according to a flight tracking website, and the ground stops were not expected to be lifted until at least 10 p.m.

Loudoun County fire officials turned the building back over to the FAA about 9 p.m., the FAA said. The agency said in a statement late Monday night that air traffic control operations resumed at the Leesburg facility about 9:30 p.m.

“Flights that were delayed are beginning to take off, and we expect to resume normal operations in the morning,” the statement read.

Loudoun County fire department spokeswoman Laura Rinehart said the facility was evacuated about 6:30 p.m. Monday after several people complained of fumes. Rinehart said that roofing work was being performed in the area, and fumes from an adhesive traveled into an air-conditioning system, resulting in the odor in the control room. Fifty-one people were evaluated on the scene, Rinehart said, and one woman was taken to a local hospital as a precuation for possible exposure.

FAA said the facility, which directs high altitude flights over the region, passed airborne flights off to other air traffic control facilities for “safe handling.”

“We are actively working to fully ventilate the facility,” the FAA said.

The evacuation, at the facility that directs high-altitude air traffic for the region’s three airports, was expected to impact flights in the region well into the night.

The Leesburg facility handles the travel of airplanes once they reach cruising altitude, which can range anywhere from above 20,000 feet up to 39,000 feet. Commercial flight involves a series of three handoffs among controllers, with airport tower controllers handling planes underway on the ground, an FAA Terminal Radar Approach Control Facility (TRACON) working with pilots transiting to and from altitude, and centers like Leesburg dealing with flights at altitude.

The Washington Center is the third-busiest in the U.S., covering 165,000 square miles that include North Carolina, Virginia, New Jersey, Delaware, Maryland, West Virginia and Pennsylvania.

The Metropolitan Washington Airports Authority advised passengers to expect delays at Reagan National, Dulles International and Baltimore-Washington International Marshall airports. According to flight tracking website Flight Aware, Reagan National Airport saw departure delays averaging two hours. Delays out of Dulles surpassed 90 minutes on average and were growing, the site said. As of 8:30 p.m., the site said, BWI was experiencing departure delays of nearly 90 minutes.

Officials at all three area airports urged passengers to check with their airline about the status of their flight.

At Reagan National, passengers aboard an American Airlines flight bound for New York’s John F. Kennedy International Airport that was slated to depart at 5:45 p.m. were still waiting to depart an hour later.

From the window of the plane, passengers said they could see a long line of planes waiting as well. Passengers, however were lucky — the plane was one of the few allowed to depart just after 7 p.m.

By 8:15 p.m. Monday night, passenger Jon Selsley, 46, of Oakland, Calif, said he was watching his third in-flight movie, “Lion.” His San Francisco-bound flight, originally scheduled to depart at 5:15 p.m., had yet to take off from Dulles International Airport. The flight was initially delayed becuase of weather issues, he said, and then the air traffic control problems hit.

Passengers learned of the control center evacuation from news reports, he said. The cabin crew and flight attendants had simply told them there was an Air Traffic Control hold.

After an extended period of taxiing, the plane pulled back into gate C12 late Monday night, Selsley said.

“They’ve let people deplane and some people seem really frustrated getting off the plane,” he said. “For a while,” he said of gate C12, “that’s our neighborhood.”

Lori Aratani and Ashley Halsey III contributed to this report.