A large manhunt is underway in the British capital, after a lone attacker stabbed four people in the back before making good his escape.
The incident happened in the Edmonton area. At least two of the victims are said to be in a serious condition.
The attacker is described as black male of around 6ft in height and thin build. He was wearing dark clothing, including a hooded top.
Authorities say that the attacks appeared to be random, and are not said to be considering terrorism as a possible motive.