A MASSIVE manhunt was under way last night for the gunmen who murdered a female police officer and seriously injured another during an armed robbery at a travel agents.

West Yorkshire Police confirmed that those responsible for the shooting, in Bradford, were still on the run, with dozens of officers deployed to track them down.

The officer who died, who was thought to be in her mid-30s, 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.

Prime Minister Tony Blair was said last night to be shocked and saddened to hear of the fatal shooting.

"His thoughts go out to the family and friends of the officers involved and to West Yorkshire Police," a Downing Street spokesman said.

Home Secretary Charles Clarke expressed his sympathies to both officers' friends and family, and to West Yorkshire Police.

"This is a terrible tragedy for them all," he said. "While incidents of this sort are mercifully rare, they serve to remind us of the risks and dangers police officers face every day in their work to uphold the law and protect the public.

"I pay tribute to their continuing bravery and dedication."

The officer was shot dead after she and a colleague were called to the scene of an armed robbery in Morley Street, in Bradford city centre, at 3.25pm.

There was no confirmation last night of reports that either she, or her injured colleague, or possibly both, may have been probationers - officers with less than two years' service.

The officer who was shot dead is believed to have been based at Eccleshill police station, in the north of the city.

One report of the shooting suggested that members of staff at the family-run business were hit in the face during the raid and money was taken.

Another witness described how attempts had been made at the scene to resuscitate the police officer.

The extent of the second female officer's injuries was also unclear, although sources indicated they might not be life threatening. She was being treated at Bradford Royal Infirmary.

Jan Berry, chairman of the Police Federation, which represents rank-and-file officers, said: "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.