British Transport Police said the cause "is not currently being treated as suspicious."
London Tube station evacuated amid reports of smoke
One of the busiest stations on London's underground train system was evacuated on Friday morning after a train carriage filled with smoke.
London's fire department said crews were investigating "smoke issuing at platform level" at Oxford Circus station in one of the busiest shopping entertainment districts of central London..
Passenger Tom Singer tweeted a photograph of smoke filling a carriage of a Bakerloo Line train at the station. Another photo posted by Joe Bunting showed passengers in a smoky subway car covering their mouths and noses.
British Transport Police said its officers were on the scene but the cause "is not currently being treated as suspicious."
Passengers say staff ordered everyone to leave just before 9am on Friday. There were no reports of injuries.