In a statement, London’s Metropolitan Police said that two people had suffered stab injuries, but their conditions are not life-threatening or life-changing.
A London Ambulance Service spokeswoman said two people had been treated at the scene and one patient has been taken to a "major trauma centre." The other is being treated at hospital.
Police confirmed the incident is not being treated as terror related and there is no evidence of firearms being involved. One person has been arrested.
Witnesses said the altercation involved two men fighting in the canteen "running around chasing each other… slashing each other up."
London's Evening Standard newspaper, which also has offices on Derry Street, reports that one of the men was seen standing over his victim, repeatedly stabbing at him before he was stopped by colleagues. Another eyewitness reported seeing "blood everywhere."
Video footage of the incident, filmed through the window of an adjacent office and circulated on online, appears to show a number of armed police storming the building through the front door.
A heavy police presence remained at the building throughout Friday morning with a number of nearby roads closed.
In a statement, a spokesperson for Sony Music confirmed "there was an incident at Derry Street resulting in the building being evacuated. Two members of the catering team were involved in a violent altercation. The incident is now in the hands of the Metropolitan Police."
This story will be updated as more information becomes available.