Straphangers were trapped in a smoke-filled 7 train to Queens when loose bolts on the third rail caused the frightening situation in a tunnel, authorities said Tuesday.
The riders were left stranded for 20 minutes as smoke filled the cars.
Many passengers covered their faces with their jackets and shirts, and some took to social media to shoot video and pictures of the smoky scene.
The smoke kicked up around 11 p.m. on Monday, according to the MTA. A motorman heard a pop before the smoke went into the cars.
An FDNY spokeswoman said the tracks did not catch on fire — but riders said they were left in the dark about what was causing the scary fumes.
“Fire on the 7 train. Trapped underground for 30 minutes,” tweeted passenger Jason Tseng. “Smoke filled train. No announcements. #subwayfire.”
Another rider took to Instagram to post a video of the smoky car.
“Almost died on the 7 train!!!” wrote Bapesageneral. “Big ass explosion came at us, I was on the first cart too #7train explosion.”
The short clip showed riders shielding their faces.
The MTA said fans pumped air into the train cars to clear the smoke, and no one was injured.
It wasn’t clear how many cars were affected, the MTA added.