A Red Line Metro train carrying more than 50 passengers was stranded underground between stations for about an hour yesterday morning, and traffic above ground was disrupted while firefighters searched unsuccessfully for a source of smoke reported in the tunnel, officials said.

No smoke or fire was discovered between the Tenleytown and Friendship Heights stations, but service along the Red Line was disrupted from 8 to 10 a.m., and about 15 pieces of firefighting and rescue equipment clogged Wisconsin Avenue.

The train was stopped after firefighters ordered its operator to take them into the tunnel where an earlier train operator had reported smoke.

As the train moved north between Tenleytown and Friendship Heights, other fire personnel ordered Metro to cut power to the third rail between the two stations--standard procedure when firefighters are on the scene. The third rail powers the trains with 750 volts of electricity.

Before the power could be restored, dozens of firefighters on the scene had to be accounted for, officials said. That process took almost an hour.

D.C. Deputy Fire Chief Phillip Pestone said the fire department supervisor on the scene who decided to take an occupied train into an area where smoke had been reported probably was in error. But Pestone said the decision was made only after the fire supervisor and Metro officials had conferred and concluded there was no fire danger.

"I don't believe people were ever put in harm's way," Pestone said. "There was a miscommunication."

Metro officials agreed there was never any danger for passengers, only inconvenience. Metro riders were diverted to buses running between the two stops until service was restored shortly after 10 a.m., Metro spokeswoman Cheryl Johnson said.

The incident began shortly before 8 a.m., when Metro starts its Saturday service. Johnson said an operator of an outbound train reported seeing smoke. The fire department was called, and Metro sent two trains without passengers on inbound tracks at reduced speeds to investigate, she said.

"They saw nothing," she said, adding that Metro had already decided there was no problem and was planning to continue service. "We had already determined amongst ourselves that there was no emergency."

But when firefighters arrived on the scene, they needed to independently assess the situation, which caused the disruptions.