London’s Oxford Circus underground station in the heart of the British capital’s main shopping district was being evacuated on Friday evening and armed police were on the scene, a Reuters witness said.

British Transport Police said its officers were at the station, responding to an incident.

“The station is currently closed, please avoid the area at this time,” BTP said on Twitter.

The Reuters witness said the area around the station had been cleared of people and traffic. Fire engines were heading towards the scene, the witness added.

The capital’s transport operator, Transport for London, said trains were not stopping at the station due to the unspecified incident.