The Federal Aviation Administration resumed traffic at Reagan Washington National Airport on Tuesday after briefly halting operations because of a bomb threat against a United Airlines plane.

The FAA said operations were resuming after earlier issuing a ground stop due to a reported security issue.

Passengers were removed from the plane, and the aircraft was moved away from the terminal while authorities investigated.

A person briefed on the matter said a bomb threat had been made against the plane and in an abundance of caution the plane was being checked.

United referred questions to the FBI. The FBI did not immediately respond to a request for comment.

Reagan Airport is just five miles from the White House and US Capitol and the FAA imposes special security restrictions around the airspace.

FlightRadar24, a flight tracking site, said the issue was prompted by an unconfirmed threat against a United flight that had arrived from Houston.

More than 190 flights have already been delayed at Reagan Airport, according to FlightAware.