London's Oxford Circus underground station in the heart of the British capital's main shopping district was being evacuated. 

According media reports, armed police were on the scene.

British Transport Police said officers were on the scene responding to an incident but gave no further details.

The police warned people to avoid the area, in London's West End.

"Oxford Circus Station is closed while we investigate a customer incident," Transport for London said.

Further details are awaiting.