What we know:

• Police have stood down after officers were called to London's Oxford Circus Tube station at about 16:38 GMT to numerous reports of shots being fired
• Police said there was no evidence of gun fire
• One woman sustained a minor injury when leaving Oxford Circus station
• Oxford Circus and Bond Street Tube stations have reopened
• Extra officers will remain on duty in the West End this evening

Our main story will continue to be updated. Read more here.

Crowds are back at Oxford Circus Underground station after it reopens.

Image source, Reuters

Crowds are pictured going into Oxford Circus Tube station, as it reopens following the police incident.

Image source, Rebecca Willcox

Transport for London has said Oxford Circus and Bond Street stations have reopened, but there has been some confusion as a cordon remains in place.

British Transport Police said it is working to lift the police cordon in Oxford Circus and reopen the station.

British Transport Police say officers were called to Oxford Circus Tube station following reports of gun fire on the westbound Central Line platform.

"Passengers at the station then self-evacuated the station onto Oxford Circus and Regent Street area of London," a statement said.

"This caused a significant level of panic which resulted in numerous calls from members of the public reporting gunfire. "Officers responded in line with our procedures of a terrorist incident, this included armed officers from British Transport Police and the Metropolitan Police.

"A full and methodical search of the station and Oxford Street was conducted by officers.

"At this stage, we are examining the circumstances of the incident which resulted in the station being evacuated. "During the station evacuation, one woman is believed to have sustained a minor injury."

BBC News correspondent Richard Lister is in Oxford Street and says the street is “extremely quiet”.

He says he can see lots of police, but no ambulances and it is “relatively calm”.

Image source, PA

Buildings in the Oxford Circus area are in lockdown, including the BBC's New Broadcasting House.

The Metropolitan Police says in a statement:

"To date police have not located any trace of any suspects, evidence of shots fired or casualties.

"Officers continue to work with colleagues from British Transport Police in the area of Oxford Circus.

"Updates will be provided as soon as we have them.

"If you are in building stay in a building, if you are on the street in Oxford Street leave the area.

"Officers are continuing to search the area."

BBC journalist Alex Regan says he was initially barricaded inside a nearby pub when news of the incident broke.

He says: "There was a mad dash towards the basement of the pub as people heard the news of an incident. There were some people crying."

He adds that the street outside now seems calm but "people are understandably shaken".

Jon Donnison, BBC News correspondent, says there are dozens of police vehicles in Oxford Circus and "more arriving all the time".

He says shops have been evacuated in the area.

It was "absolutely packed" in and around Oxford Street because of Black Friday, he says.