WASHINGTON -- Metro has found the cause of the door malfunction on the 3000 series rail on Wednesday. All of the cars are cleared to return to service. 

On Tuesday, Metro pulled all of its 3000-series trains from service after a rider posted a video from inside one of the railcars that showed a door partially stuck open.

RELATED: Metro pulls all 3000 series cars from service after door malfunction report

Metro General Manager Paul Wiedefeld said a train door stuck open “poses a significant safety risk,” and ordered 274 of the trains be taken to a railyard in West Falls Church for investigation.

“This is exactly what a safety culture looks like,” said Wiedefeld.

An analysis of the Tuesday morning rush by MetroHero found that trains most trains arrived at least two minutes later than scheduled, amounting to about ten percent reduction of service across the system. Wiedefeld underscored that significant overcrowding was avoided by pressing extra trains into service.

RELATED: Metro to start running Yellow Line trains to Greenbelt on Saturday

Now that the 3000 series cars have been inspected, they have all been cleared to return for service Wednesday.  No further service impacts are expected. 

More details on cause will follow.