Thousands of homebound Metrorail passengers endured long delays traveling between the District and Virginia on Tuesday evening after a train derailed at the Rosslyn station, creating a severe bottleneck.

No injuries were reported after the derailment, which occurred shortly after 7 p.m., but all service passing through Rosslyn was suspended for 20 to 30 minutes. Metro then began single-tracking service.

Full service was restored by Wednesday morning.

Rosslyn is a key transfer point. Blue and Orange line tracks diverge just outside the station, and a switch sends trains on each of the lines in the proper direction. Switch points on rail systems are generally considered among the sections of track most vulnerable to derailment.

The cause of the derailment was not known immediately. Metro said it apparently involved only one set of wheels in the front car of a Blue Line train headed for Franconia-Springfield, which had just left the Rosslyn station. The six-car train was carrying about 1,000 people at the time. It was not known how close the train was to the switch.

Metro said the last four cars of the train were still alongside the Rosslyn platform at the time of the derailment, which Stessel described as minor. He said it took about 10 minutes for passengers to get off the train.

At first, Metro said it would provide buses that would shuttle passengers around Rosslyn, taking Blue Line passengers between Foggy Bottom and Arlington Cemetery, and Orange Line passengers between Foggy Bottom and Clarendon.

When trains began running with limited service, there was confusion among passengers who had left the rail system in search of buses, only to be told that trains were again operating.

Jennifer Bost said she waited outside a station in the District for the promised shuttle bus. After 10 minutes, she headed to a stop for a regularly scheduled bus to Virginia. It provided a crowded and chaotic trip.

At first, she said, some passengers boarded “but refused to pay” because they thought the bus, on the 38 route, was one of the free shuttles. The bus quickly filled, leaving passengers “packed together like sardines.”

When the bus driver tried to let one of the passengers off at a scheduled stop, Bost said, about 40 people were waiting outside, “pushing to get on.”

“I’m full,” the driver told them.

Bost estimated that the trip home took 95 minutes longer than usual.

The Tri-State Oversight Committee, which monitors Metro safety, said it sent personnel to the scene to help Metro in the investigation. The National Transportation Safety Board was notified, Metro officials said.