Tributes have been pouring in for Fiona Bone and Nicola Hughes, the policewomen believed to have been gunned down by fugitive Dale Cregan in Tameside, Greater Manchester.
Greater Manchester Police Chief constable Sir Peter Fahy described Ms Hughes as a "chatterbox" and a "great bobby" who was "always smiling".
He said Miss Bone was a "calm, gentle woman", an "excellent bobby" and had been in the middle of planning her wedding.
Thirty-two-year-old Fiona Bone and 23-year-old Nicola Hughes were killed after they responded to reports of a burglary
Sir Peter, speaking at a press conference at GMP headquarters, said the force was "absolutely devastated" by the shootings, adding: "We are all shocked by what happened this morning."
Fiona Bone, 32, who had served with the police for five years, was "so happy" with her partner and had been planning her wedding.
Sir Peter said: "When she first joined the shift she was quite quiet and reserved. However she came out of her shell and had a great sense of humour, always enjoying a good laugh.
"She was so happy with her partner and they were in the middle of planning their wedding. Indeed her partner only spoke to her this morning about the wedding invites and fellow officers gave her advice about how to make them on the computer.
"Her fellow officers said that they always loved being partnered off with her as she was always calm, collected and professional, and could defuse situations with her calm, gentle way. She was an excellent bobby, and cared about her job, and the community she served."
Nicola Hughes, 23, who had served for three years, was described as a "bubbly" woman who "loved socialising".
The chief constable said: "Nicola enjoyed karate. She was bubbly and loved life and socialising. She was a chatterbox and was always smiling, even after a night shift when everyone else was a bit grumpy. She was a good listener and could not do enough for people. She was a lovely friend, and a great bobby."
In a statement released by 10 Downing Street, Mr Cameron said: "The killing of two police officers in Manchester is a shocking reminder of the debt we owe to those who put themselves in danger to keep us safe and secure.
"I want to offer my thoughts, along with those of the whole country, to the families, friends and colleagues at this difficult time."
Thousands of people took to Twitter to pay their respects to Ms Hughes and Bone.
User Rich Wiltshir said: "I salute Fiona Bone, Nicola Hughes & hardworking honourable police officers everywhere. Sad loss at hands of a thug."
Michael Winstanley wrote: "Very saddened by the news of the death of Fiona Bone & Nicola Hughes. Two brave & dedicated GMP police officers."
And Diverse Diva tweeted: "RIP Fiona Bone & Nicola Hughes. Two heroines who took a bullet to protect us all. Tragic."
Greater Manchester Police, meanwhile, has opened an online book of condolence for the public.