POLICE have arrested a second man in connection with the brutal killing of two policewomen in an attack which has shocked the nation and prompted more than 45,000 messages of condolence.

Greater Manchester Police (GMP) said the 28-year-old had been detained in Hattersley on suspicion of conspiracy to murder following the deaths of PC Nicola Hughes, 23, and PC Fiona Bone, 32, in a gun and grenade assault.

Dale Cregan, 29, handed himself in shortly after the killings and is being questioned over the officers' deaths and the murders of father and son David and Mark Short.

The WPCs are believed to have been lured to their deaths by a fake burglary call-out which appeared to be a routine check.

GMP chief constable, Sir Peter Fahy, said the outpouring of public support in the wake of the tragedy had left the force overwhelmed. So far, more than 25,000 messages of condolence have been posted on the force's website, while 19,000 tributes appeared on Facebook and 1000 on Twitter.

Messages have flooded in from dignitaries around the UK and last night Manchester United players wore black arm bands during their Champions League match against Galatasaray at Old Trafford.

Sir Peter said: "We have been overwhelmed by the huge degree of public support we have had following the sad deaths of our two officers.

"I would like to thank the public for this tremendous show of support, it means a huge amount to us at this difficult time.

"Clearly the whole force, and indeed the whole police service, is devastated by the deaths of these two brave colleagues.

"But to know at this difficult time the public support what we do and feel so strongly about the sacrifice of these officers, and are giving such support to their family, is important to us."

The Queen has sent a letter to the force offering her sincere condolences for the tragic loss of lives.

GMP officers held a minute's silence at 11am yesterday – almost exactly 24 hours after the attack.

The chief constable warned that officers remain under threat as not all explosive devices may have been recovered from the scene. Sir Peter said: "We are not confident we have recovered all the grenades, we don't know for certain, so we have made it clear to our officers that the threat is still there.

"I would want that to be the message. This has been a long-standing criminal feud between different outfits in Manchester and in the Tameside area, and that threat is very much there."

He added that the force had issued Osman warnings – notices given to people under threat of being murdered or seriously injured – to "a large number of individuals".

Ms Bone – whose family have flown over from the Isle of Man – died at the scene of the attack, while Ms Hughes died a short time later in hospital.

Sir Peter said the force's main priority had been to support their families "who clearly have a huge amount to come to terms with". He added: "I would like to say how impressed we've been by the dignity of these families.

"Both have said how proud they were of Nicola and Fiona, and how proud those two officers were to serve the public. Both families have separately said their loved ones died doing the job they loved."

Ms Hughes's family said they were exceedingly proud of her, adding: "We cannot express how we feel. She knew she was loved by us all and we shall all miss her dreadfully."

Ms Bone, who was planning a civil ceremony with her same-sex partner, was described as a kind, loving, gentle, funny, caring woman.

In a search of the area after the attack, which eyewitnesses described as a hail of bullets, one of the officers' tasers was found on the ground out of its holster.

Floral tributes have been left at the scene, including one from Manchester City Football Club.

Home Secretary Theresa May has had talks with the Chief Constable.