“Is @OneWTC on fire right now?” a Brooklynite tweeted Tuesday night.

The alarm and the ghost of 9/11 terrorist attacks spread across social media in the metro region and even outside the state, but NYPD and fire officials said it was just steam rising from the Freedom Tower’s heating units.

Several photos and videos of the steam, some with a slight orange-red tinge, went viral on Twitter and in newsfeeds early Tuesday evening.

“We can confirm that there is no fire to report at the WTC,” FDNY tweeted about 7 p.m.

A “suffering Mets fan” tweeted: “Okay so its looking like 1 WTC is in fact not on fire. If you’ll excuse me, I need to rapidly re-age 15 years.”

Another Brooklynite tweeted his own observation: “After getting the binoculars out I’m upgrading the condition of the #wtc from ‘on fire’ to ‘probably not on fire.’ ”

Marsha Landar, a former businesswoman from Queens Village, said the incident brought back memories of the World Trade Center burning during the 2001 terrorism attacks.

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“It’s such an eerie thing,” Landar, 57, now a health care aide, told Newsday. “Just to see that was kind of weird. It’s just a lot a memories.”