Video footage captured from inside a Tube carriage shows clouds of smoke and what appears to be an alarm sounding following an incident on Friday (August 11) morning.
Oxford Circus was evacuated on as firefighters attended to investigate reports of smoke, in an incident described by one passenger as "intense" and "scary".
London Fire Brigade has confirmed there was a "small fire" on a Tube train, with around 15 firefighters from Paddington and Lambeth fire stations attending the incident following calls at 8.47am on Friday.
A spokesman from London Fire Brigade said: "Firefighters dealt with a small fire on a train on the Bakerloo line at Oxford Circus.
"The station was evacuated before the brigade arrived."
Further footage released shows emergency services at the scene in Oxford Circus and London Ambulance Service (LAS) has confirmed two people have been taken to hospital as a precaution.
An LAS spokesman said: "We sent an ambulance crew, our Hazardous Area Response Team and an incident response officer to the scene, with the first of our medics arriving in less than five minutes.
"We treated four patients at the scene for smoke inhalation and have taken two of them to hospital as a precaution."
An anonymous eyewitness spoke to getwestlondon about her experience during the evacuation
She said: "At the time they said security alert and it was really intense and scary.
"Everyone got really pushy and shovey and it was intense."
She explained staff wanted "everyone out as quick as possible" and described the experience as "scary."
British Transport Police has said the cause of the fire is not currently being treated as suspicious.
According to the Bakerloo Line Twitter account, service on the line has resumed with severe delays and Oxford Circus Tube station has reopened.
On their website, Transport for London write: "Severe delays due to an earlier fire alert at Oxford Circus.
"London Underground tickets will be accepted on SouthEastern Trains, Thameslink and local bus services."
Passengers are being advised to head to the Transport for London website for assistance in re-planning their journey.
To catch up with the events as they unfolded, head to our live blog .
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