POLICE chiefs vowed last night to hunt down the armed robbers who murdered a female officer and left another seriously injured.

The shooting happened at a travel agents in Bradford yesterday afternoon. Three suspects were seen fleeing the scene and were still on the run last night.

Assistant Chief Constable David Crompton told a news conference: "Every single member of West Yorkshire Police, from the chief constable to the newest recruit, is absolutely determined they will catch the people responsible for this crime."

Asked if both officers were probationers, Mr Crompton said: "Yes, both officers were in their first two years of service."

The officer who died is the third female officer to be killed while on duty in the past 20 years.

She is also the second officer from the West Yorkshire force to have been murdered in the past two years.

The killing comes almost two years after the force lost PC Ian Broadhurst, 34, who was murdered by David Bieber, 38, in Leeds, on Boxing Day 2003.

Bieber was later tracked down to the Royal Hotel, in Dunston, Gateshead.

Detective Superintendent Andy Brennan told last night's news conference: "At about 3.30pm, a personal attack alarm was activated at the Universal Express Travel Agents, on 116-120 Morley Street, Bradford.

"The nearest officers to respond to that report of the alarm activation were two unarmed female officers in their 30s.

"We know that, as the officers arrived at the travel agents, up to three men ran from the premises. One shot was fired by this group of men which hit one of the officers, which has since proved fatal.

"Several other shots were fired, one of which hit the second officer, resulting in serious gunshot injuries. These injuries are not life-threatening."

Earlier, a Downing Street spokesman said: "The Prime Minister was shocked and saddened to hear of the tragic events in Bradford.

"His thoughts go out to the family and friends of the officers involved and to West Yorkshire Police force."

Home Secretary Charles Clarke said: "I am shocked and saddened to learn that a police officer has been killed while on duty in Bradford, and her colleague injured.

"My sincere sympathies go to both officers' friends and family and to West Yorkshire Police."

Jan Berry, chairman of the Police Federation, which represents rank-and-file officers, said: "Our thoughts are with the family, friends and colleagues of these officers.

"This tragic death of a constable so young in service is the second murder of a police officer in West Yorkshire in the last two years, and shows how dangerous policing can be when you are called upon to protect your community, never knowing what you may face.

"The professionalism of West Yorkshire Police will ensure that the coward who took this brave officer's life is brought to justice."

Tom McGhie, chairman of West Yorkshire Police Federation, described the officer's death as a terrible tragedy and extended his sympathies to her family.

"We will be doing everything possible to support that family and her colleagues because I am sure they will be affected by this tragedy," he said.

The shooting is likely to reopen the debate over whether all frontline police officers should be routinely armed.

PC Norman Brennan, director of Protect the Protectors, said: "If police officers are to retain the highest confidence of the public and their own morale, surely the time has come for them to be able to defend themselves and the British public with every means possible.

"If that includes the routine carrying of firearms, then so be it."

The scene of the shooting remained cordoned off last night and a number of roads in Bradford city centre were also closed.

Police were asking people to avoid the area.

Within the cordon, more than a dozen officers, some of them armed and others wearing protective vests, were on patrol.