It happened at the end of the morning rush hour.
A Metro Red Line train was traveling through the tunnel between Tenleytown and Van Ness when the doors on two cars opened up.
Despite it being a packed car, no one was injured. Metro says it's been years since anything like that has happened.
The cars were the 1000 series, the oldest in Metros fleet, and the same series involved in the fatal 2009 crash. Metro officials say Tuesday morning's train was taken out of service and engineers are looking into the problem. the 1000 series make up a quarter of metros fleet, but so far no plans to pull them out of service.
"They should get that fixed ASAP," says one passenger. "They're working on a lot of things hopefully that's one of them they can work on too."