WASHINGTON — Metro said human error caused the doors of a Yellow Line train to open before it reached the platform Tuesday.

Metro confirmed the incident Wednesday and said a preliminary investigation showed human error caused doors to open before it entered the Reagan National Airport station Tuesday afternoon. There is a button a train operator can press to open the doors.

The train was stopped at the time, but not yet in the station.

The train operator has been taken out of service until the investigation is completed.