The MTA has suspended L train service between First Avenue in Manhattan and Morgan Avenue in Brooklyn, after gas fumes caused at least two passengers to faint.

Update: L train service is suspended between 8 Av and Myrtle Wyckoff Avs while we investigate the source of fuel smells on the tracks near Graham Av. Our safety checks have found that the air is currently safe, but we need to correct and resolve the condition. (1/3) pic.twitter.com/i0zRBFVe50 — NYCT Subway (@NYCTSubway) February 5, 2019

Rachel Pincus tells Gothamist she noticed the fumes on Monday, but thought that perhaps her sense of smell was too sensitive. This morning, she was taking the L into Manhattan around 10:45 a.m. when the train stopped and stalled in Lorimer for 15 to 20 minutes, "the fumes just started wafting in."

"After quite a while, a young woman standing near me fainted and a bunch of passengers rushed to get her into a seat, where she eventually regained consciousness," Pincus said. "The train continued to crawl after that, prolonging our suffering, and I saw another woman covering her nose and mouth after that."

Pincus, who is a former Gothamist intern, said it made her feel like "a canary in a coal mine."

"I have been riding the subway for so long and I've endured so many weird and awful smells but this was the first one that actually made me want to throw up!"

The Daily News reports that another person fainted this morning when the L approached the First Avenue station.

Yet another L train rider emailed Gothamist to say that "the L has smelled like diesel for the past 2 days between Lorimer and Jefferson." The rider, Cristin Hughes, added, "It’s super noticeable at Morgan. People are complaining of headaches."

WNYC reporter Rebeca Ibarra noticed the same thing, and was told by a transit authority Twitter account that the smell was from diesel trains performing overnight work.

Good morning. We apologize for the smell; street-level waterproofing work was done at Bedford Av yesterday and several diesel trains were in the tunnel last night working on tracks and switches. Fans are running to clear the air, and our crews are continuing to investigate. ^JLP — NYCT Subway (@NYCTSubway) February 5, 2019

Hughes says she and her boyfriend first noticed it at Morgan "and it got stronger at Graham, then dissipated at Bedford. The smell was incredibly strong and was similar to diesel or turpentine (a cleaner of some kind), it smelled like a large amount of it spilled. At first we thought it was possibly in the train car, like someone walked in covered in it. It smelled exactly the same a few hours later on the way back. It was making us light headed and it felt like if we stayed on longer it would make us nauseous.

The odor was observable this morning as well, Hughes says. "Things smelled off again with the odor returning strongly at Graham," according to Hughes's boyfriend. "It smelled more like a burning smell, maybe metal or even some kind of plastic. The train stopped at Graham around 11:50 am for close to ten minutes. He thinks he heard on the conductor's radio that the last stop on that train was going to be Bedford."

An MTA spokesperson has not yet responded to our request for comment.

In Williamsburg doing an interview when all of a sudden we were evacuated from L train platform due to suspected gas leak. (We could smell it) @CBSNewYork pic.twitter.com/rgQHagNVBz — Alice Gainer (@GainerTV) February 5, 2019

In the meantime, the MTA says shuttle buses are being "mobilized," but to find alternate modes of transportation. There is normal L train service between Myrtle-Wyckoff and Canarsie-Rockaway Parkway, and "limited" service between First Avenue and 8th Avenue.

[UPDATE / 3:20 p.m.] Another passenger who lives off the Grand Street stop in Williamsburg tells Gothamist that she has vomited several times since the smell made her sick on the train this morning.

Christina Pettit said she took the L train on Monday evening and noticed the smell.

"It really just smelled like a strong chemical odor to me, not indicative of gas or typical gasoline smell," Pettit said. "I woke up this morning and I was like, yeah I kinda feel nauseous." But she took the L train to work from Grand Street again on Tuesday morning, and the smell was still present.

By the time she settled in to her office, Pettit said she knew she was going to be ill. "I was racing to go up to the second floor bathroom, and I did not make it," Pettit said.

"My doctor told me I could have had a reaction to it, and I'll just have to let it pass," she added.

Initially, Pettit said she was happy that the MTA found a way to avoid a total L train shutdown, and that she was confident that the agency could mitigate the silica dust and other safety issues that the new L train repair plan would present.

"I did until today," Pettit said. 'I'm really starting to second guess both their tactics and also their inability to inform people. I smelled this last night, I'm sure that people did. I'm sure people driving the trains smelled it, and they're the ones stuck in the tunnels all day. I'm sure the station workers smelled it."

Pettit added, "I can only assume they didn't want to disrupt the morning commute, but now here we are."

[UPDATE / 3:26 p.m.] The MTA now says that L train service has resumed, and that they have determined the source of the smells.

L and J train service is resuming in both directions after determining the source of fuel smells near Graham Av. State DEC and FDNY crews determined it to be safe, but lingering smells may be present at stations in that area. https://t.co/ovJmTljf7M — NYCT Subway (@NYCTSubway) February 5, 2019

Their explanation contradicts what they tweeted earlier, that the smell was from "street-level waterproofing work" and "several diesel trains" that had been doing overnight work in the L train tunnel.

The investigation determined that the smell was caused by heating oil that leaked into the system from an external source. ^HKD — NYCT Subway (@NYCTSubway) February 5, 2019

“The MTA’s two most basic responsibilities are to provide reliable service and to protect riders’ health," Manhattan State Senator Brad Hoylman said in a statement. "It is infuriating and disturbing that they are are failing on both counts. If riders can’t trust the MTA to take care of the basics, then how can we take them at their word on the new L Train plan or anything else?”

[UPDATE / 4:00 p.m.] The MTA says that initially, they believed the smells were caused by leftover fumes from the diesel trains. When the fumes did not dissipate, they began investigating the cause.

"Service was suspended while FDNY and DEP thoroughly examined what appeared to be an oil or gas leak at the Graham Station, at track level," MTA chief external affairs officer Max Young said in a statement. "Both Departments have confirmed that non-flammable heating oil from an external source had leaked onto the track and the incident is completely unrelated to the L train project or any other MTA construction."

Young continued, "Air quality at all stations has been tested and determined to be safe. We apologize to our customers for the delay in service - their safety is always our number one priority and we would never compromise it.”

Additional reporting by Paula Mejía.