A United Airlines flight attendant deployed an emergency evacuation slide on an airplane after it arrived in Houston and used it to exit a plane packed with passengers, an airline official said on Tuesday.

"It is our understanding that she deployed it intentionally," said United Airlines spokesman Charlie Hobart, adding airline officials have been speaking with the flight attendant to see why she deployed the slide in the incident that took place on Monday.

In a video shown on Houston TV station KPRC, the flight attendant tosses her bag out of a door behind the cockpit and slides down the slide. She grabs the bag and walks away from the plane, which was at full stop.

A photo of the airplane on the station's website shows it at the gate, with the slide deployed on the side opposite of the gate.

The flight, with 159 passengers and six crew members aboard, was from Sacramento to Houston's George Bush Intercontinental Airport. The airplane, a Boeing 737-900, was briefly taken out of service for maintenance and then was returned to its scheduled use.

The flight attendant, who was not identified by the airline, has been removed from flying duties. All the others aboard exited the plane without incident or injury.