A police officer has been stabbed with a machete in a “frenzied” attack as he tried to stop a van in Leyton, east London.
The officer, aged in his 30s, was stabbed multiple times but managed to use his Taser to subdue the suspect.
His colleague then stepped in to arrest the suspect following the stabbing, shortly after midnight.
Police said he was expected to recover from his injuries.
The uniformed officers had attempted to stop a van on the junction between Coopers Lane and Leyton High Road, the Met said.
The vehicle had initially failed to stop but the driver then suddenly pulled over got out and injured the officer, the force said.
Insp Julia James, from North East Command Unit, said: “This was a sudden and brutal attack on a uniformed officer carrying out their duties.
“What began as a routine vehicle stop has transformed very quickly and unexpectedly into an unprovoked attack with a weapon.”
A man, aged in his 50s, was arrested at the scene on suspicion of GBH and taken to an east London police station for questioning.
In the wake of the attack, pictures posted on social media showed a heavy police presence in the Leyton area.
Police said there was nothing to suggest the incident was terrorism-related.