All inbound and outbound planes were halted briefly at Reagan National Airport on Sunday afternoon while federal safety officials investigated a bomb threat.

US Airways flight 2596 from Dayton, Ohio, was nearing Washington when someone made the threat at the ticket counter in Dayton, according to the FBI. That person was detained.

The plane landed safely at 1 p.m. and was immediately diverted to a remote part of the airport. All other flights were delayed for about 20 minutes, said a spokeswoman for the Metropolitan Washington Airports Authority.

Investigators interviewed the 44 passengers onboard, and bomb experts swept the plane but found nothing hazardous, the FBI reported.

Two hours after the plane landed, it was visible from the terminal and still surrounded by flashing lights.

The spokeswoman for the airports authority said that a few US Airways Express flights were delayed later in the afternoon but that most flights resumed their normal schedules shortly after the initial delay.

The incident is the fourth aviation-related security issue in eight days. The most recent incident occurred Saturday, when a small aircraft entered restricted airspace around the nation’s capital.