A traffic warden was grabbed by the throat and kicked in the head after issuing a parking ticket.
The victim and a colleague were patrolling in The Broadway, Woodford Green, yesterday when violence flared.
After the ticket was issued, an argument ensued between the wardens and the driver and a passenger in the car at around 3.30pm, near Woodford Tube station.
Witnesses said the passenger then jumped out of the car and grabbed the warden by the throat.
The driver then kicked the same warden in the legs and head, leaving him on the floor.
A member of the public then dragged the attacker off and police were called.
The two men drove off and police gave chase, but the attackers managed to lose them.
The injured traffic warden has been taken to hospital.
More to follow.