Metro is investigating a malfunction with the doors on one train Monday evening.
At about 6 p.m., doors on one car of a Huntington-bound Yellow Line train opened while the train was traveling across the Potomac River. A rider said the doors opened about 3 inches, but Metro workers testing the doors could only open the door three-quarters of an inch, according to Metro.
After the doors opened, the car was emptied and isolated at Pentagon Station. Officials asked riders in that car to move to one of the other five cars on the train and locked the car and turned off the lights. Workers began to test the car when the train arrived at Huntington Station.
The incident caused a 7-minute delay. No one was injured.
Metro workers are testing the car's electrical and mechanical systems.