A bomb threat against a United Airlines flight prompted a brief closure at Ronald Reagan Washington National Airport and forced passengers on the plane to evacuate onto the tarmac.

The FBI investigated the incident and said that no credible threat existed.

"The FBI Washington Field Office's National Capital Response Squad responded to reports of a bomb threat at Ronald Reagan Washington National Airport today. No hazards were found," a statement from the agency said. "The FBI continues to work with our law enforcement partners on this investigation."

United Airlines acknowledged the incident in a statement to USA TODAY.

"United flight 512 landed safely after a potential security concern. Customers deplaned via airstairs and were bused to the terminal. Law enforcement officials searched and cleared the aircraft and it has since taxied to the gate," the airline's statement said.

The flight was en route to DCA from Houston (IAH). The Boeing 737 Max 8 aircraft had 89 passengers and six crewmembers onboard.

Photos on social media showed passengers from the flight walking on the tarmac at DCA.

The Federal Aviation Administration put a ground stop in place affecting flights departing for the airport, but expected that pause to end around 3:30 p.m. ET.

Zach Wichter is a travel reporter and writes the Cruising Altitude column for USA TODAY. He is based in New York and you can reach him at zwichter@usatoday.com.

This article originally appeared on USA TODAY: Bomb threat prompts United plane evacuation, ground stop at DCA

Reporting by Zach Wichter, USA TODAY / USA TODAY

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