Witnesses have spoken of their horror at the shooting dead of a female police officer following an armed robbery at a travel agents in Bradford.
Walwah Ditta, a local businessman, told BBC News: "This is not on. This is a cruel act."
He added: "It's scary. The whole thing has freaked me out."
Local man Geoff Kendal said of the shooting, in which another female Pc was injured: "It's quite a shocking incident, being so close to home."
A BBC correspondent said the whole area had been shut down.
A fellow police officer was seen crying near the scene of the shooting, on Morley Street.
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.
"This is a terrible tragedy for them all. I know the thoughts of everyone across the police service and indeed the nation will be with them at this difficult time.
"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."
Councillor Khadam Hussain, whose ward covers the area where the shooting happened, said: "It is appalling. I really feel for the family. It is shocking."
Another councillor, Sajawal Hussein, said: "On the whole, the relationship between the police and the community is very good in this area."
'Should be armed'
Film director Michael Winner, who founded the Police Memorial Trust after the 1984 shooting of WPc Yvonne Fletcher, said: "I'm afraid it's not unusual that a normal day becomes a day of tragedy for police women and men.
"They are massively at risk and the only way to protect them is to give them body armour at all times or to arm them.
"I think they should be armed."
Keith Hellawell, the former chief constable of West Yorkshire police, said: "It is extremely sad.
"These things happen rarely, thankfully, but when they do the whole family of policing throughout the country is in mourning.
"And I think every sensible and honourable human being will recognise the sacrifice police officers make and the potential danger they are in every day that they walk out on the streets."
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."