Passengers pour onto the Tenleytown Metro platform Saturday after a train is evacuated due to a track fire near Friendship Heights. (Sarah Alaoui)

A track fire on Metro’s Red Line that frightened riders and caused long service delays over the weekend involved “a metal part of a rail car becoming dislodged and making contact with the electrified third rail,” the transit agency said Monday.

“While Metro has not yet identified the root cause of the incident, investigators have eliminated power cables as a contributing factor,” the agency said in a statement. It said that a “foreign object” came loose from a subway car. When the “foreign object” made contact with the third rail, “a loud noise, flash and smoke” resulted.

The incident occurred shortly before 7:30 p.m. Saturday in a tunnel near the Red Line’s Friendship Heights station.

Appearing before a D.C. Council committee Monday, Metro General Manager Paul J. Wiedefeld said the agency was still trying to determine the precise cause of the incident. Smoke began seeping into an eight-car train that had halted in the tunnel, evoking memories of a fatal calamity Jan. 12, 2015, near the L’Enfant Plaza station.

[Frightened Red Line riders evacuated after tunnel fire.]

In the Red Line incident, officials and witnesses said, the Shady Grove-bound train stopped for about 10 minutes after encountering the smoke. It then backed up to the Tenleytown-AU station, where riders, some of them terrified, were safely evacuated.

“At approximately 7:19 p.m. . . . the operator of Red Line train No. 107 traveling outbound reported hearing a loud boom and smoke entering the lead car,” Metro said.

“Passengers were moved into the trailing cars of the train. The train operator was instructed to reverse direction and was given permission to move back to Tenleytown station, where the train was offloaded,” the statement said.

It said: “Prior to the train being moved, an unknown passenger pulled an emergency door release, causing the train to lose ‘all doors closed’ indication. It was confirmed that no passengers ‘self evacuated’ from the train. Once all doors were confirmed closed, the train was moved.”

At a regularly scheduled meeting of the council’s finance committee, D.C. Council member Jack Evans (D-Ward 2) — who also has been chairman of Metro’s governing board since January — asked Wiedefeld about a story in Monday’s Washington Post that detailed decades of mistakes by Metro, including lax subway maintenance.

[Decades of institutional neglect made Metro an embarrassment.]

“The deferred maintenance, we have to do something, in my estimation — something different than what we have been doing,” said Wiedefeld, who became Metro’s top manager in November. “We’re just not catching up as quickly as we need to. Some of the issues you saw Saturday could be related to some of that.”

Unlike the Red Line train, the Yellow Line train in the L’Enfant Plaza incident last year was unable to back up, and scores of riders were sickened as noxious fumes poured into the cars. One passenger died from respiratory failure.

The fire near the L’Enfant Plaza station was related to faulty power cables in the tunnel, as was a recent tunnel fire near the McPherson Square station, officials said. That fire, in which no one was hurt, prompted Wiedefeld to close the subway system for 24 hours March 16 so work crews could repair and replace deteriorated cables.

[At heart of Metro shutdown, worries about uncontained electricity]

Saturday’s Red Line incident did not involve faulty cables, Metro said. As for the exact cause, Wiedefeld said, “I just do not want to make any assumptions on that yet.”

Council member Elissa Silverman (I-At Large) asked whether it was possible that the dangerous problem could recur. “You are confident people should continue riding the Red Line, feeling safe?” she asked Wiedefeld.

“Yes,” he replied.

“Okay, great,” Silverman said.

Wiedefeld has said he will soon announce a comprehensive plan for systematically overhauling subway infrastructure, a process that will involve closing sections of the rail system for perhaps days at a time, to allow for work to be done.

At a regional conference last month on Metro’s problems, Evans said entire subway lines might have to be shut down for six months. Wiedefeld later contradicted him, saying his overhaul plan would not involve such drastic steps.

“Nobody liked the idea,” Evans said Monday, referring to his remarks about a long-term shutdown. “Everybody was up in arms, front page of the newspaper, can’t close a whole line for six months. Okay, then somewhere between those two extremes, of closing a line and doing what we’re doing now. We have to figure out a way.”