A police officer has been seriously injured after being stabbed a number times with a machete in a "sudden and brutal attack."
The patrol officer was stabbed at around midnight on Thursday after attempting to stop a van in Leyton, east London.
The vehicle's driver, aged in his 50s, initially failed to stop but when it eventually halted, he got out of the van and injured the officer with the machete, Scotland Yard said.
Detective Chief Superintendent Richard Tucker, who described the attack as "frenzied and unprovoked", said the officer is "seriously injured, but he will make a recovery".
The policeman managed to use his Taser despite having been stabbed, with the alleged attacker then arrested by another officer.
The injured officer, aged in his 30s, was taken to hospital by ambulance.
He is being treated for a wound to the side of his head, which requires stitches, and an injured hand from fending off the attacker.
The driver, who did not require hospital treatment, has been arrested on suspicion of grievous bodily harm and taken to an east London police station.
A crime scene remains in place in the area.
Police have said there is nothing to suggest the incident is terrorism-related.
North East Command Unit's inspector Julia James described the assault as a "sudden and brutal attack".
She added: "What began as a routine vehicle stop has transformed very quickly and unexpectedly into an unprovoked attack with a weapon.
"Our thoughts are with the injured officer and his family and we wish him a full recovery.
"I would like to commend his bravery and resilience especially as he managed to draw a Taser, despite being repeatedly stabbed, to prevent the suspect harming anyone else and to protect himself from further injury," she said.
"This incident highlights the very real risk that police officers can be confronted with on a daily basis and the courage and professionalism officers demonstrate when doing their job."
