Several arriving flights were delayed Monday night at Dulles International Airport while police conducted an investigation there, an airport spokesman said.
Metropolitan Washington Airports Authority spokesman Rob Yingling said that so far as he knew, departures were not affected.
He said the investigation involved two parking garages, which were closed to the public, and remained so at 10 p.m. Areas used for some incoming flights were also affected for a time.
Yingling declined to disclose details of the investigation.
The delays involved several flights scheduled to arrive between 8:30 and 9 p.m. he said. At 10 p.m., officials said flights were operating normally.
No injuries or arrests were reported.
This report has been updated.