Armed police have been stood down following reports of shots fired on London's Oxford Street and at Oxford Circus Tube station.
Cordons have been lifted on Oxford Street, where shoppers were earlier warned to "go into a building" amid fears over a possible terror-related incident.
Oxford Circus and Bond Street stations have also now been reopened.
Met Police said: "Given the nature of the information received, the Met responded in line with our existing operation as if the incident was terrorism, including the deployment of armed officers.
"Officers working with colleagues from British Transport Police carried out an urgent search of the area.
"No causalities, evidence of any shots fired or any suspects were located by police."
There was one report of a woman sustaining a minor injury when leaving Oxford Circus station.
British Transport Police said there was "a significant level of panic", adding that it was "examining the circumstances of the incident which resulted in the station being evacuated".
Pictures and video on social media showed armed police at the station and people being led away from Oxford Street.
Some reported being caught in "stampedes" near Oxford Circus Tube station after the alert.
Armed police also evacuated Selfridges, but the department store has said it was a precautionary measure and there were "no reported incidents in store".
Kensington Palace said the alert delayed the arrival of the Duke and Duchess of Cambridge to the Royal Variety Performance at London Palladium.
Bryce Malcolmson, who works in Soho, said he was in Oxford Circus Tube station when he heard a call over the loudspeaker for a police officer to attend one of the platforms.
He told Sky News: "Suddenly I just heard screaming and people running out of the station. Everybody turned round in sort of pandemonium and started trying to exit the Tube as quickly as possible.
"I got up to the top by the ticket barriers and they were all open. I ran out on to the street but it was almost as if no one knew anything had happened down below.
"Within…a couple of minutes there were armed response units and police cars absolutely everywhere. I think people were so unsure what had happened they were running in all directions."
Tourist Lanna Woodward said she witnessed the aftermath of panic on Oxford Street.
The 20-year-old, from California, said: "Before it all I saw about 30 police officers speeding down the street.
"We were in the Kingdom of Sweets and then saw a massive crowd of people running and screaming. People were climbing on top of each other.
"The store we were in was locked down, the manager wouldn't let us leave - they said there had been a shooting at the entrance of the Tube station."
Paying tribute to the "swift response" of emergency services, city mayor Sadiq Khan urged Londoners to "remain vigilant and don't panic".
He said: "It is vital that we are not complacent - if in doubt it is always best to err on the side of caution and call the police on 999."