AVRUPALONDON - The Met said they were responding as if the incident was terrorist related and have told people on nearby Oxford Street to take cover inside buildings.
"Oxford Circus Station is closed while we investigate a customer incident," Transport for London said.
BBC reporter Helen Bushby said she had seen a "mass stampede" of people running away from the station.
People were "screaming and crying", she said.
She spoke to a group of young women at Topshop, on Oxford Street, who said people had dropped their shopping and ran as quickly as they could.
In a statement on Twitter, British Transport Police said: "We continue to respond to an incident at Oxford Circus.
"The station is currently closed, please avoid the area at this time. Officers are on scene."