‘Aliens’ descend on New York City as bizarre power explosion confuses onlookers

A giant plume of smoke coloured bright blue has exploded into the night sky sparking calls of "aliens" across New York City.

The bizarre sight set social media a frenzy, as authorities tried to work out what was going on at 9.30pm on Thursday night.

It turns out, aliens weren’t descending in Queens – a transformer had blown at a power station.

La Guardia Airport was closed temporarily as the explosion was brought under control.

Trains were also delayed for a time.

The blow-out led to about 50 power outages.

The press secretary for New York City mayor confirmed via Twitter that the blue sky was "*Not* aliens".