A man has been arrested after armed police responded to two people being stabbed in central London, Scotland Yard has said.
The two were stabbed after an argument broke out between kitchen staff at Sony's headquarters, employees of the company said.
Firearms officers descended on Derry Street at about 11am.
The Metropolitan Police said the injured people are not believed to be in life-threatening conditions.
It is not being treated as "terror related", police said.
"We just heard screaming and running and people slamming doors," said a Sony employee, who did not want to be named.
The men, who are employed by a catering company, were "running round chasing each other", he added.
UPDATE: Incident on Derry Street, W8- One person arrested. Two people with stab injuries. No evidence of firearms involved. Not being treated as terror related. https://t.co/R9fA2LdAX8 pic.twitter.com/LhD6HJkmXQ— Metropolitan Police (@metpoliceuk) November 2, 2018
Footage filmed from an office opposite showed a number of armed police entering the building through the front door.
Trish Ellis, who works at the Mail on Sunday and who witnessed the incident, said: "It started opposite our building in Derry Street, usual sirens and racket but then we heard shouting, and more and more sirens.
"A few people came out, then armed police were going in six-plus at a time, and more and more of them, but they seemed to be keeping people in the building.
"Gradually they started to release people in tens, 20s, and a stretcher turned up with all the medical kit on it, but just stayed outside."
According to the Evening Standard, which is based by the scene, a witness reported seeing panicked people running from the incident while screaming.
"Large crowds of people began exiting the building's front door at around 11 o'clock," the onlooker said.
"Most were running, all towards Kensington Square Garden. Several were visibly panicked and some were screaming."
Scotland Yard said: "Officers, including firearms officers, and London Ambulance Service are in attendance.
"Evacuations have taken place as a precaution. One person has been arrested.