World Trade Center steam prompts fears of fire

It was a pretty scary sight Tuesday night: what looked like a fire atop One World Trade Center. It turned out to be a combination of steam and light. The optical illusion alarmed people on social media, who tweeted that the top of the tower appeared to be on fire.

The FDNY and Port Authority confirmed that the building was not on fire. An official said that steam from the HVAC system at the top of the tower can appear to look like smoke.