Police were called at 3.25pm to the travel agents in Morley Street in Bradford where PC Sharon Beshenivsky was shot and fatally wounded during a bungled robbery on November 18 2005 at the age of 38.
Since then, six men have been jailed in connection with her murder.
West Yorkshire Police Federation chairman Brian Booth laid a wreath in remembrance at her memorial, which was unveiled in 2009 by former Prime Minister Gordon Brown.West Yorkshire Police Federation wrote in a tweet: "Remembering PC Sharon Beshenivsky, of West Yorkshire Police. Murdered on duty on this day in 2005. #LestWeForget"
Connor Gurney said in a tweet: "13 years on, we today remember the sacrifice of PC Sharon Beshenivsky who was brutally murdered in a hail of gunfire in Bradford. She gave her life so that members of the public may live, and we must never forget that."
John Sutherland wrote: "Today, I am remembering PC Sharon Beshenivsky, who was gunned down in the street thirteen years ago today... Rest peacefully brave one."