A man with a sword was arrested in Hainault, east of London, after several people were attacked and injured, the Metropolitan Police said on Tuesday.
The force said it was called just before 7:00 am (0600 GMT) after a vehicle drove into a house and reports that "people have been stabbed".
"At this time we understand the suspect went on to attack other members of the public and two police officers," a statement read.
"We are awaiting an update on the condition of those injured."
The Met, which polices an area of 620 square miles (1,605 square kilometres) of Greater London, said a 36-year-old man was arrested at the scene.
Deputy Assistant Commissioner Ade Adelekan said: "This incident does not appear to be terror-related."