The Prime Minister has paid tribute to the "totally selfless" policeman who was shot dead in Clacton after he's believed to have intervened in a dispute while off-duty.
David Cameron said PC Ian Dibell's death was a reminder of the "immense debt" the nation owed its police officers.
The officer, dubbed a hero by colleagues, was killed and another man injured in the double shooting on Monday afternoon.
Mr Cameron said the thoughts of the whole country were with PC Dibell's family.
Speaking in Downing Street during a press conference with French President Francois Hollande, he said: "It is the first time I have been able to comment on the very sad death of police constable Ian Dibell, who was killed yesterday in Essex.
"He was off-duty but went to help people in a totally selfless and typical way that our police officers do all of the time.
"It's a reminder of the immense debt that we owe them and what they do on our behalf and I just want to pay tribute to him and say that the whole country, I'm sure, is thinking of his family and his friends at this difficult time."
Nick Clegg also paid tribute at Deputy Prime Minister's questions in the Commons, saying: "I am sure the whole House will join me in offering our deepest sympathies to the family of Pc Ian Dibell and his colleagues in Essex Police.
"Police officers keep us safe day in day out. They act when they see public safety at risk, whether or not they are on duty.
"PC Dibell was a dedicated professional who has sadly paid the ultimate price."