As subway service slowly gets back to normal following Friday's derailment in Queens, the MTA is releasing more information about that section of rail involved.
The MTA says they've discovered a small fracture in the rail under the train.
The agency says the rail was manufactured in 2013 and installed this past March.
The rail is being removed and sent for testing.
Officials said it appears the crew on board the train was not responsible in any way.
Crews were still at work Saturday cleaning up the area and replacing the damaged track.
Workers were trying to remove a handful of cars on the F train that derailed Friday morning.
"They're leaning, and they have to get put back on the rails and pulled to where there are existing rails that they can get on to," said MTA spokesperson Adam Lisberg. "Then, you have to get those train cars out."
After service interruptions throughout most of the morning, several lines had more service restored Saturday afternoon, while other lines still waited for restorations.
According to the MTA, there was no R train service between Forest Hills-71st Avenue in Queens and 57th Street-7th Avenue in Manhattan as of 5:30 p.m. Saturday.
The MTA advised customers to transfer to a Queens-bound F train at 34th Street-Herald Square. The F train will operate as a local and make all stops between 21st Street - Queensbridge and Jamaica - 179th Street.
According to the MTA, the E train will also operate as a local and make all local stops between Queens Plaza and Jamaica Station - Parsons/Archer.
The MTA says those changes to E and F service will be in effect until 10 p.m. Saturday. At that time, the agency will suspend local E and F service along the line through 10 a.m. Sunday to remove the remaining cars and complete track repairs.
"You have to go in and start rebuilding the track," Lisberg said. "That could mean putting in a new base for it, putting new rails in, putting a new third rail in. You have to test it all, make sure it's going to work."
Shuttle buses will be provided for commuters using the lines during that time.
The MTA says work to repair tracks will extend into early Monday with the goal of restoring full normal service on all affected subway lines by the Monday morning rush.
Though service was ramping back up Saturday, commuters NY1 talked to said they're having a tough time getting around town.
"This is ridiculous," said one commuter. "This is already the second day. I didn't even make it to work yesterday."
"I was waiting for the 7 train. Four trains came, but they were so packed that you literally couldn't get on the train, so I came back out, and now, I'm going to take the shuttle bus," said another. "And I was supposed to be at work at 9:30."
"Horrible. Horrible," said a third. "Because that announcement guy wasn't very clear, I went in there, went downstairs, came back up because the train wasn't there."
MTA officials sympathized with riders but said these inconveniences will hopefully mean fully restored service by Monday.
"This stop here in Jackson Heights is super busy in the mornings," said one commuter. "It's really crowded, and if the F train isn't working, it would probably be a nightmare come rush hour on Monday. So if they have it ready by Monday, that's great."
More than 1,000 passengers were evacuated from the underground tunnel when the train derailed at approximately 10:30 a.m. Friday.
The New York City Fire Department says 15 people suffered minor injuries and were treated at the scene.
Another four were brought to nearby hospitals with more serious injuries, mostly from smoke inhalation.
Transit officials said six of the eight cars jumped the tracks.