Metrorail service was delayed Tuesday night between Washington and Virginia on the Blue and Orange lines after a train derailed near Rosslyn, authorities said. No injuries were reported.

The derailment occurred around 7:15 p.m., after the peak of the evening rush period, but at a time when the system is still heavily used.

Metro reported that it had suspended all service through the tunnel under the Potomac River for a time after the derailment. But by about 7:40 p.m., it said service had been restored, using a single track for both directions.

However, Metro warned in a statement at about 8 p.m. that “it will be a while before service gets back to normal.” Officials suggested that some Virginia- bound passengers could take the Yellow Line to the Pentagon and transfer there to the Blue Line. They also suggested taking the Red Line to Farragut Square and transferring to the 38 bus to Virginia.

Metro officials said passengers on the derailed train had been returned to the Rosslyn station and removed from the train.

Dan Stessel, Metro’s chief spokesman, said the derailment was minor, citing the lack of injuries. The incident occurred on the Blue Line headed to Franconia, just outside the Rosslyn station.

The cause of the derailment was not immediately known.

A Metro employee said the "wheels on the front car of the train derailed" while the rest of the train was on the tracks. The person said there was some work done Tuesday, before the incident, on a "switch problem" near where the derailment occurred. The person said initial reports inside Metro were calling it a "misalignment of a switch."
But Stessel said there have been no official findings of the cause, and that it is "way too early to know that."

The Tri-State Oversight Committee said it sent personnel to the scene to help Metro in the investigation.

Metro has had recent problems with cracked rails on some of its tracks and brake systems on some of its trains.
In January and December, brake parts fell from trains in two incidents.

The December incident, which occurred during morning rush, shut down service along the downtown core of the Orange and Blue lines for hours. Metro pulled the cars from service and examined them for “hub failure,” the same type of problem that had occurred before.

Metro said the rail car involved in the derailment is in the 3000 series. The incidents involving brake friction rings in December involved a 5000 series train. The brake friction incident in January involved a 2000 series rail car.

The derailment comes three years after the deadliest crash in Metro's history on the Red Line. Even after that, there are no federal standards for transit systems. More than 40 rail agencies across the country set their own rules and procedures.

This report has been updated.