Police were called to Gale Street, Dagenham, at 6.18pm on Monday, 17 August to reports of a road traffic collision and a stabbing.
Officers attended along with paramedics from London Ambulance Service (LAS).
It was reported that two cars had collided and a man inside one of the vehicles had then been stabbed.
The victim and the suspect(s) had left the scene before police arrived.
A short time later, a man in his 20s, attended an east London hospital with stab injuries.
Police await an update on his condition.
A crime scene is in place. There have been no arrests.