Two people were taken to hospital after a fire broke out on a train at a Tube station.

An electrical fault caused grey smoke to billow out of the Bakerloo line train as passengers stood in dark, smoke-filled carriages covering their faces with items of clothing.

People waiting on the platform also covered their mouths and noses.

Oxford Circus station, which services London’s busiest shopping street and sees thousands of commuters pass through it during the rush-hour, was closed after the incident.

Commuters cover their mouths as smoke fills the carriage (Joe Bunting)Commuters cover their mouths as smoke fills the carriage (Joe Bunting)

Transport for London confirmed the fire was caused by an electrical fault and said a “comprehensive investigation” will take place.

Nigel Holness, London Underground’s director of network operations, said: “The cause of the smoke was an electrical fault under one of the carriages, which resulted in a small fire that was quickly extinguished. Understandably this was a distressing incident for our customers, for which I give my sincere apologies.

“A comprehensive investigation into how this incident could have occurred is now under way.

“Our Sarah Hope Line, which is set up to help those affected by incidents on the transport network, is also available to offer support.”

A London Ambulance Service spokesman said medics were called at 8.53am on Friday to reports of an incident on board a Bakerloo line train at Oxford Circus Tube station.

He added: “We treated four patients at the scene for smoke inhalation and have taken two to hospital as a precaution.”

A video taken by a passenger appears to show the Tube train in a tunnel and an alarm can be heard beeping.

Fiona Crosy tweeted: “Very scary moment on the Bakerloo: emergency alert at Oxford Circus and then as we went through the tunnel the carriage filled with smoke.”

While @lucyjanefunnell posted: “There’s a fire at #OxfordCircus tube. Bakerloo line is on fire and you can smell the black smoke going through. Hope everyone is ok!”