London - British police were on Tuesday hunting a gunman who shot and killed an off-duty officer after he intervened in a "deadly situation".
Police were called to Farlop Close in Clacton, east of London, at about 15:30 on Monday after gunshots were reported.
They found constable Ian Dibell, 41, dead at the scene along with another man who had sustained gunshot wounds to the leg.
Officers said they were looking for Peter Reeve, 64, in connection with the shooting and warned he was dangerous and should not be approached.
Essex Police Chief Constable Jim Barker-McCardle said Dibell was "a highly regarded and much loved colleague who has been an important part of Essex Police for 10 years".
"The entire force grieves but we are aware the job is to bring this man to justice and make sure we do everything we can to look after most important people, the family and friends of our fallen colleague," he added.
Barker-McCardle stressed that he was unaware of the "fine details" of the incident, but that it appeared Dibell had "deliberately intervened in what I strongly believe he knew was an extremely deadly situation."
Shadow Home Secretary Yvette Cooper said she was "shocked and appalled" by the shooting.