'We heard an explosion': Union Square subway station evacuated as track catches fire

This was the moment Union Square subway station in New York City was engulfed in smoke and subsequently evacuated after debris on the track cause a fire.

In footage captured yesterday (April 9) commuters on the 4 Train were evacuated out of the station.

The fire was caused by debris on the tracks according to an NYC Transit spokesperson.

The filmer explained to Newsflare: "I was on my way to work on the 4 train this morning, while stopped at the Union Square station we heard an explosion.

"People got out of the train car to investigate when someone shouted to evacuate the station.

"Police and firefighters came down as us passengers started to make our way out of the smoke; some more panicked than others.

"I walked from the 4 line to the R line to continue my way to work"

A spokesperson for the NYPD confirmed there was "sound of an explosion".