A train came off the track near the East Falls Church Metro station platform in Northern Virginia on July 29, disrupting the morning commute for passengers. There were no serious injuries. (Video: Lee Powell / The Washington Post; Photo: Christian K. Lee/ The Washington Post)

The East Falls Church station will be closed through Sunday as Metro officials investigate a derailment on the tracks serving the Orange and Silver lines that delayed thousands of morning commuters and capped off an already troubled week for the system.

Though they had hoped to reopen the lines by Sunday morning, Metro officials said Saturday that they needed more time to investigate the derailment. Service will be suspended between West Falls Church/McLean and Ballston through Sunday, but will resume normal service starting 5 a.m. Monday.

The Friday morning derailment resulted in no serious injuries but startled the 60 passengers on the train. It also sent a wave of service interruptions throughout the subway system and did little to allay riders’ concerns about the system’s safety record.

General Manager Paul J. Wiedefeld said experts from Metro, the National Transportation Safety Board and the Federal Transit Administration, as well as an outside consultant brought in by the transit agency, are looking into several possibilities as to why the train derailed.

“Environment, heat — we had a lot of rain the past few days,” he said. “It starts with the human [factor]. We’re looking at ties, at fasteners, at all the switches. All that will be looked at.”

Social media video and photos show the aftermath of a train that derailed near the East Falls Church station. No injuries were reported. (Claritza Jimenez/The Washington Post)

The derailment occurred at an inopportune juncture. Single-tracking had already been in place along that segment of the Orange and Silver lines because of SafeTrack maintenance work, although the site of the derailment was not one of the work locations.

“It was totally outside of the SafeTrack zone,” Wiedefeld said. “That area had not been touched.”

In a statement, Metro said the derailed cars were removed from the tracks Friday night. Further inspection then revealed that the derailment made a portion of the track to shift, causing more damage than had been anticipated. Officials said that 200 feet of rail have to be replaced, along with 150 feet of the electrified third rail. Two track crossings also have to be replaced, along with 200 wooden track ties.

Metro officials already were dealing with revelations about a “near miss” on July 5, the latest ­red-signal violation — this time at Reagan National Airport; backlash over a proposal to cancel late-night weekend service; and early grousing about the 17-day single-tracking scheduled to start Monday on the Red Line.

Then, Friday morning brought the derailment and delays on the Red, Green and Yellow lines.

The East Falls Church station mishap occurred at 6:15 a.m. at an interlocking area on the system’s Silver Line. The train was headed to the Wiehle-Reston East station when the fourth and fifth cars went off the tracks, stopping the train 120 feet from the platform, Metro officials said. Wiedefeld said the derailment caused significant damage to the tracks, traction power system and two rail cars.

A contractor was expected to move the train Friday afternoon, an effort that requires diesel-powered prime movers in addition to a crane to lift the damaged rail cars.

The outside consultant specializes in derailments and will help determine why the train derailed.

“We’re going to find out what the root cause of this is,” Wiedefeld said. “And to do that, we do not want to move any of the equipment.”

“Safety has to trump service,” he added, a phrase that has become one of his signature lines.

Until that process is finished, Metro will run shuttle buses between the Ballston and West Falls Church stations on the Orange Line and between the Ballston and McLean stations on the Silver Line.

Although there were no serious injuries, one passenger went to the hospital.

Chandler Davis, 36, had been leaning his head against the window on the right side of the train to try to catch a few extra minutes of sleep. Suddenly, the train tilted to the right, slammed to the left and then tilted right again, he recalled. His head banged against the window, and he later learned that he had suffered a concussion. Davis said it took about five minutes for a Metro employee to enter the train and assist passengers.

In the interim, people were panicked.

“There were screams and confusion,” Davis said. It took 15 to 20 minutes for passengers to be evacuated from the train, he added.

Another passenger, Santo Butler, 37, of Arlington, recalled feeling “a couple of larger bumps” in the moments before the derailment.

“We skidded towards the fence,” Butler said. There was a “burst of sparks from outside the train, and we all knew what happened and that it could have been worse.”

Later in the day, as the afternoon rush picked up, the line for shuttle buses outside Ballston grew immensely, eventually stretching half a block.

Mykia Washington, 18, said the derailment added an extra 90 minutes to her commute from Wiehle-Reston to Friendship Heights, where she works at a bank. She had left her home around 6 a.m. and arrived close to 9. In the afternoon, when trains let out at Ballston, she had to board a Silver Line shuttle bus to continue her trip home.

“It’s frustrating, because I’m an intern,” she said. “I have to get to work on time, or it’s going to look bad.”

According to Metro officials, the transit agency had 14 derailments between 2011 and August 2015, when a train left the tracks between the Smithsonian and Federal Center stations shortly before the start of passenger service. Of those, four were on the main rail system and 10 were in rail yards.

Friday’s derailment will be a significant test for Metro’s incoming chief safety officer, Patrick Lavin, who has been on the job for just over two months after Wiedefeld recruited him from New York City Transit.

One of his major steps since arriving has been to assign six Metro employees to dedicate their time to investigate accidents, such as the one Friday, and identify ways to prevent future ones.

The derailment also shines a light on the FTA’s role as a temporary safety oversight body — and whether the added level of federal supervision has led to tangible improvements in safety.

The FTA has conducted more than 200 inspections of the Metrorail system since taking temporary responsibility for safety oversight in October. It has found more than 1,100 defects — instances in which Metro officials failed to follow their own safety procedures or protocols.

Even so, the transit agency’s problems have continued. In the past month alone, there were three instances in which train operators ran through red signals.

Earlier this month, members of the House Oversight Committee sent a letter to the Government Accountability Office to explore whether the Federal Railroad Administration, rather than the Federal Transit Administration, should have oversight of Metro’s rail system.

That question has been a source of tension between Transportation Secretary Anthony Foxx and NTSB members, who say they think that the FRA — another agency within the Department of Transportation — is better suited to oversee the safety of the nation’s second-busiest subway system. That’s because the FRA has decades of experience overseeing the safety of the nation’s railroads. Federal oversight is a temporary measure for assuring the safety of Metro’s rail system until a new state oversight board can be created.

“My view is, give us the most rigorous regulatory enforcement that’s available,” said Rep. Gerald E. Connolly (D-Va.), one of the signatories of the letter. “The FRA has more resources, more capability, more rigorous standards. But for whatever reason, Foxx rejected that. I just feel if we’re going to put safety first, let’s put safety first.”

For their part, FTA officials said they are continuing their push to make Metro a safer system.

“FTA continues to find safety problems throughout the system and is directing [the Washington Metropolitan Area Transit Authority] to make repairs, but Metrorail’s problems will not be fixed overnight,” Steve Kulm, a spokesman for the FTA, said in an emailed statement. “The Tri-State Oversight Commission did not demand accountability at WMATA on these critical safety issues, which is why the FTA had to step in temporarily. We are working with WMATA to improve their safety protocols and training programs. WMATA must continue to focus every day on making Metrorail safer and more reliable.”

Dana Hedgpeth and Tauhid Chappell contributed to this report.