A spokesman for the Metropolitan Police said no arrest has yet been made.
He said: "A murder inquiry is now under way and an incident room will open in due course under detectives from the Specialist Crime and Operations Directorate.
"We must retain an open mind re the circumstances of the incident and any motive at this early stage."
Anyone with any information can call police on 101 or contact Crimestoppers anonymously on 0800 555 111.
More top news
Ex-London mayor Ken Livingstone says he is sorry for the "disruption" caused by his comments that Adolf Hitler was a supporter of Zionism.
Kickstarter group asks for public donations to fund replacing Tube ads with pictures of cats
Sir David Attenborough opens Woodberry wetlands in Stoke Newington