The incident at Oxford Circus Tube station that sparked a mass evacuation was caused by an “altercation” between two men, British Transport Police said.
Several people were injured and nine were taken to hospital, including one with leg injuries, after panic erupted in the packed station on Friday.
Armed police raced to Oxford Circus Tube station and Oxford Street after receiving 999 calls reporting that shots had been fired.
British Transport Police said the incident is believed to have started with an altercation between two men on the platform.
A British Transport Police (BTP) spokesman said: “Officers alongside colleagues from Metropolitan Police Service were called to the station at 4.37pm today following reports of shots fired.
“Armed officers from BTP and MPS were quickly on scene. The area was searched swiftly and the station was reopened. Officers believe an altercation erupted between two men on the platform.
“They would now like to speak to these two people in the CCTV images, who they believe may have information about the incident and the circumstances around the incident.
(PA Graphics)
“They would also like to speak to anyone who was at the station or in the area at the time and saw or heard anything that would have caused mass evacuation.”
Chief Superintendent Martin Fry said: “Thank you to everyone for bearing with us this evening and also to colleagues from all the emergency services who helped carry out a swift response.
“I know incidents like these can cause concern, but our officers are highly visible around the network and across the country.”
There was panic among rush-hour commuters and Black Friday shoppers in central London, with a number of people injured.
Stuart Crichton, London Ambulance Service assistant director of operations, said: “We checked over and treated several patients who sustained injuries while leaving the Oxford Circus area.
“We discharged seven patients at the scene and took eight patients to two central London hospitals for minor injuries.
“We also took one patient to a major trauma centre for leg injuries.”
Around 90 minutes after responding, police said there was no evidence of any shots, casualties or suspects.
The station was reopened, cordons removed and the area returned to normal, including the Royal Variety Performance at the nearby London Palladium going ahead as planned.
In a statement the Met 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 casualties, evidence of any shots fired or any suspects were located by police.”
Describing the panic, BBC producer Helen Bushby said: “I was just walking down from the BBC towards the Tube and there was a mass stampede away from the Tube as fast as they could.
“They were crying, they were screaming, they were dropping their shopping bags. It was a very panicked scene.
“People said they heard a gunshot and panic was just spreading.”
Anyone with any information can contact BTP on 0800 40 50 40 or text 61016 with reference 405 of 24/11.