Flights Grounded at Washington DC Airport Due to ‘Security Threat'

A ground stop at one of America's most prominent airports took place on Tuesday, halting air traffic and keeping passengers out of the sky for some time. Two aviation sources tell NBC News that several planes were forced to divert landings to other airports as a result.

The ground stop comes as airports around the country continue to experience delays and slowdowns due to the ongoing government shutdown.

The Metropolitan Washington Airports Authority says that United Airlines flight 512 left Houston for Washington on Tuesday morning and landed at around 11:30 a.m. The MWAA says the flight "stopped on an adjacent runway away from the terminal in response to a security threat."

Passengers on the Tarmac Tuesday

Video from the scene showed passengers leaving a United Airlines plane and walking along the tarmac, and buses were nearby to pick the passengers up. Police were also near the scene with flashing lights from their vehicles.

The Federal Aviation Administration (FAA) says that it is aware of the incident and that it is currently conducting its own investigation.

Audio obtained by LiveATC.net indicates that air traffic control was aware of an "unconfirmed bomb threat," with air traffic controllers telling flight crew "we've got to get you away from the airport."

"Someone called and said there was a bomb on 512, they said if it landed, it would explode -- well, it landed," one air traffic controller said at around 11:37 am eastern time.

After the flight landed and the ground stop was initiated, the airport released a statement on social media stating that flights would resume once those stranded passengers were bussed to the terminal.

Roughly one hour later at 12:50 eastern time, officials say that flights were resumed as scheduled with runways reopening.

Second Recent Ground Stop at DCA

This is the second time that DCA has been shut down for a ground stop in the span of a week. Last Wednesday, the FAA told news outlets that the airport was briefly shut down because "military activities" in the area would delay flights.

Other airports in the area - Washington Dulles (IAD) and Baltimore / Washington (BWI) - were not affected by the threat and proceeded as normal on Saturday.

The American airline industry and airports around the country have been heavily impacted by the government shutdown. TSA agents and air traffic controllers are reporting to work as essential employees, but they aren't being paid as the shutdown persists.

We'll see if the strain on airlines and airports around the country leads to more delays with no end to the shutdown in sight.