Three teenagers have been taken to hospital after being stabbed within minutes of each other in north-east London.
Metropolitan Police officers were called to Lukin Crescent, Waltham Forest, at 3.07pm and found a boy, believed to be 15, with a stab wound.
Twelve minutes later, they were called to nearby Westminster Gardens where two 19-year-old men were found with stab wounds.
The victims have been taken to hospital where their condition is not yet known.
Four arrests have been made, Scotland Yard said.
Prime Minister Theresa May recently held a summit on knife crime following a spate of bloodshed across London and the rest of England since the start of 2019.
Last week a man appeared in court in connection with five knife attacks that took place in Edmonton, north London.
One of the victims, a 45-year-old woman, was left paralysed after her spinal cord was severed in the attack.
Earlier this year 14-year-old Jaden Moodie was stabbed to death in Leyton, in Waltham Forest, after a group of five men in a black Mercedes rammed him off a moped, police believe.
Anyone with information is asked to call police on 101 or Crimestoppers anonymously on 0800 555 111.