Firearms officers are at the scene of an incident in central London amid reports a man with a machete has entered a building belonging to Sony Music.

Scotland Yard said: "We are aware of an incident on Derry Street W8, police on scene including firearms officers and London Ambulance Service. At this time we believe two people are injured. Incident is on-going."

Sony Music is based on Derry Street.

The incident is not being treated as terror-related and there is no evidence firearms were involved, a Metropolitan Police spokesman added.

Footage filmed from an office building opposite showed a number of armed police entering the building through the front door.

Trish Ellis, a personal assistant at the Mail on Sunday who witnessed the incident, said: "It started opposite our building in Derry St, 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, twenties, [and] a stretcher turned up with all the medical kit on it, but just stayed outside.

"A [helicopter] appeared, still loads of armed police running up and down, and then thankfully over the time it ended up much quieter with 10 armed police standing outside, at ease.

"[An] empty stretcher went away and, thank God in heaven, all seems calm again," she added.