The police officers shot in Bradford are the latest in the line of many risking their lives in the course of their work.
Yvonne Fletcher was fatally wounded outside the Libyan Embassy
Since 1900 more than 160 officers have died while on duty.
The most recent female officer to die on duty was Alison Armitage in 2001 - she was hit by a stolen car in Hollingwood, Oldham.
In October 1997 WPc Nina Mackay was stabbed to death during a raid in Stratford, East London.
Pc Yvonne Fletcher, 25, was shot dead controlling demonstrators outside the Libyan Embassy in London in April 1984.
Ian Broadhurst was shot dead in Leeds on Boxing Day 2003
Among the most famous cases is Pc Keith Blakelock, a 40-year-old father of three, who was set upon by a mob and hacked to death with a machete during the Broadwater Farm riots in Tottenham, north London in 1985.
The murder of Pc Sidney Miles in November 1952 triggered one of the most controversial episodes of British legal history - Derek Bentley, 19, was convicted of his murder and subsequently went to the gallows in 1953.
Det Con Michael Swindells, 44, died after being stabbed in the stomach as he and colleagues conducted a search in Birmingham in May 2004.
Det Con Stephen Oake died during a police raid on a flat in Crumpsall, Manchester, in January 2003. He was the victim of a frenzied knife attack.
Police officers killed by criminal acts in the line of duty since 1680 are recorded on the National Police Memorial Roll of Honour in central London.