The Federal Aviation Administration issued ground stops for several airports in the Washington, D.C., area Friday evening because of a “strong smell” at an air traffic control tower.

Temporary ground stops were issued for Ronald Reagan Washington National Airport, Washington Dulles International Airport, Baltimore-Washington International Airport, Charlottesville–Albemarle Airport and Richmond International Airport, the FAA spokesperson said.

The odor was reported at the Potomac Consolidated Terminal RADAR Approach Control, or TRACON, in Warrenton, Virginia, an agency spokesperson told The Independent.

FlightAware shows that more than 150 flights have been delayed at Baltimore’s airport so far on Friday. More than 180 flights have also been delayed at Dulles, along with more than 250 flights at Reagan National, according to the tracking website.

This comes about two weeks after a “strong odor” was reported at the same air traffic control center, triggering ground stops at nearby airports. More than 30 FAA employees were evaluated, but none needed to be taken to the hospital.

Transportation Secretary Sean Duffy said the March 13 incident was caused by an overheated circuit board.

“Firefighters from Fauquier County and Prince William County confirm there is no danger to air traffic controllers, and they are returning to the Potomac TRACON,” he wrote on X. “The source of the strong odor was traced to a circuit board that overheated, and it was replaced.”

Passengers in Washington-area airports reported lengthy delays in the aftermath.

This is a breaking news story. Check back for updates.