A Metropolitan Police firearms officer is in hospital after being mown down during a vehicle stop.
A suspect car was stopped at White Hart Lane, Tottenham, north London just after 11.30am on Tuesday and initially pulled over for police.
But the driver then sped off, hitting and injuring the officer.
The Met said he does not have life-threatening injuries, and no arrests have been made.
A local chicken shop owner in White Hart Lane, who did not wish to be named, said: “I saw the car coming… and it was flying like 100 miles an hour.
“After two minutes I saw police following and I knew it was serious.”
Dramatic CCTV footage caught minuets before the collision by a local corner shop showed the police car following a black Mercedes as it turned into White Hart Lane.
The incident follows a spate of serious attacks on police officers, including being hit by vehicles.
Thames Valley Police officer Pc Andrew Harper died when he was mown down after being called to a burglary in August, while West Midlands Pc Christopher Burnham was left with head injuries and a shattered knee when he was hit by a car in Coventry in September.
