London’s Metropolitan Police said two people had been stabbed in central London on Friday, with armed officers on the scene.
The incident happened at Sony Music UK’s head office in Kensington.
Police said they were called to the incident at Derry Street where Sony’s offices are based at about 1100 GMT.
They said one person had been arrested but the case was treated as terrorism.
“Officers, including firearms officers, and London Ambulance Service are in attendance,” police said.
“Evacuations are in place as precaution.
“Two people have suffered stab injuries – we await an update on their condition.”
Pictures on social media showed large numbers of police vehicles at the scene.
Business journalist Simon Neville wrote on Twitter that he saw a man wearing a red jacket being tackled to the ground in a loading bay on Derry Street.
“Security seemed to have him under control and closed the loading bay shutters once tackled,” he wrote.
No one from Sony was immediately available for comment.