Greater Manchester Police/AP Photo

The grief-stricken neighborhood of Mottram in Manchester, England, observed a moment of silence today as residents paid tribute to two young female police officers killed when they were lured into a grenade ambush, allegedly by a man who was out on bail for two other grenade murders.

Prayers were said for officers Nicola Hughes, 23, and Fiona Bone, 32, who were killed in a gun and grenade attack after reportedly responding to a hoax burglary report.

A police spokesperson told ABC News that the man arrested on suspicion of their murder, Dale Cregan, 29, turned himself in around midday Tuesday, allegedly confessing to the crime after he walked into Tameside police station.

"We can't keep him past 11 o'clock tonight unless we get a special warrant for another 24 hours, so we expect him to be arrested or released sometime later today," the police spokesperson said.

Cregan was arrested on suspicion of the murder of father and son in separate grenade attacks in June. He was released on bail pending further inquiries, then went into hiding and became Manchester's most wanted. Police had offered more than $80,000 as a reward for information leading to his arrest.

An eyewitness told the Manchester Evening Herald how she saw Cregan minutes after the shooting "just walking about, as any normal person would do."

The deaths of Hughes and Bone present the biggest single loss for on-duty British police officers in almost 50 years, when three detectives were gunned down in West London.

The Police Roll of Honor Trust, a charity devoted to fallen officers, said that five officers had been shot dead in the past decade.

According to the Associated Press, FBI figures show that 544 U.S. law enforcement officers were killed in the same period.

Unlike American police officers, who typically carry guns when on duty, only a limited number of police officers in Britain are authorized to carry firearms. Each police force has its own firearms unit, and according to latest government statistics, the total number is now 6,653. That's a 5 percent decrease compared to the previous year.

The number of police operations in which firearms were authorized in the last year-just over 17,000-fell 7 percent from the previous year.

Ash Rathband, the son of a police officer who was shot and blinded by a gunman in 2010, tweeted: "It's time for Police to be armed in my opinion. Yet again another awful incident :-( #officerdown."

The ambush and murder of Hughes and Bone is re-igniting the debate about whether all UK police officers should be armed when on-duty. Trained officers have all had access to Taser guns since 2004, despite controversy about their use.

The London Metropolitan Police commissioner routinely lobbies in favor of this, while the president of the Association of Chief Police Officers, a professional forum, warned against a call to arms. "You only have to look at the American experience. Many colleagues in America are lost without even drawing their gun at close ranges," Sir Hugh Ode told the BBC.

Chief Constable Sir Peter Fahy said, "This is a dark day for policing in the UK as a whole."

In a statement, Prime Minister David Cameron said, "The killing is a shocking reminder of the debt we owe to those who put themselves in danger to keep us safe and secure."