Police were called to Lukin Crescent in Chingford at 15:07hrs on Monday, 8 April to reports of a stabbing.
Officers attended and found a boy, believed to be aged 15, suffering a stab injury.
Shortly afterwards, at 15:19hrs, police were called to nearby Westminster Gardens where two 19-year-old men were found with stab wounds.
All three victims have been taken to hospital; none of the victims are in a life-threatening condition.
Four arrests have been made and crime scenes remain in place.
Enquiries are ongoing; anyone with information is asked to call 101 with CAD 4251/08APR or Crimestoppers on 0800 555 111.
