New York City's Night Sky Lit Up With 'Crazy Blue Light'

Alien invasion? Superhero movie filming? Nope -- but it still lit up New York skies, and social media.

An eerie blue light illuminated skies over NYC on Thursday evening (local time, Friday afternoon AEDT), flickering over the city.

Residents reported the blue light originating in the Astoria neighbourhood in Queens, to the east of Manhattan.

Some joked it was an alien invasion, with others theorising a chemical fire or the filming of an action blockbuster movie.

NYC residents said they heard a loud boom and felt vibrations, a CBS journalist reported.

But it was soon revealed to be an issue at a power plant in the area.

The New York Police Department tweeted that it was investigating a "transformer explosion" at a power plant in Astoria, while people closer to the scene managed to capture vision and photos better showing where the light had originated from.

The power plant owner reported there had been "a brief electrical fire", while New York mayor Bill de Blasio advised there had been no reported injuries after the "electrical surge".

Police said the fire was under control, with firefighters in attendance. The incident disrupted some train services.