Hundreds of people have observed a two-minute silence in Bradford for Pc Sharon Beshenivsky, who was killed during an armed robbery in the city.
It is a week since the mother of three children and two step-children was shot dead during the raid at a travel agents in Morley Street.
The Bishop of Bradford, the Rt Rev David James, led the public memorial service at the city's Centenary Square.
Meanwhile, police are still hunting three men regarded as prime suspects.
They are Mustaf Jama, 25, from the north Kensington area of London, and his brother Yusuf, 19, from the same area. Both are of Somali origin.
They also want to trace Muzzaker Shah, 24, who was born in Burnley but has lived in London since 2001.
Senior Police officers led by West Yorkshire Chief Constable Colin Cramphorn gathered with civil dignitaries, firefighters and ordinary members of the public for the service.
Speaking on behalf of the people of the city, Lord Mayor of Bradford Valerie Binney said the tragedy highlighted the debt owed to the police.
Pc Beshenivsky's colleagues were among those at the service
"We want to thank them most sincerely for their commitment to apprehending criminals and making Bradford a safer place to live," she said.
The Chaplain for the West Yorkshire Police Force for the Bradford area, Sam Sagar, led the prayers at the memorial service before the two-minute silence.
"Together and with one voice we gather to affirm and bless the work of the West Yorkshire Police and pray that they will be comforted by you and reassured by the immense outpouring of public respect for them," he said.
"In a place near here at this time last week there was an act of unimaginable evil that brought great darkness to this city and to our nation.
"We pray today for Sharon's family, we ask that in their grief and in their sorrow they would feel comfort in feeling your presence with them."
Pc Beshenivsky died on her youngest daughter's fourth birthday. Her family did not attend the service.