Two 15-year-old girls have been arrested on suspicion of manslaughter after a firefighter was killed tackling a blaze at a city centre hair salon.
Firefighter Stephen Hunt, 38, was part of a team responding to a fire at Paul's Hair World in Oldham Street, Manchester, when he and a colleague got into difficulties last night.
Both were pulled from the building and taken to hospital but the father-of-two was declared dead on arrival.
A spokesman for Greater Manchester Police (GMP) said: "A joint investigation into the cause of the fire is underway and two 15-year-old girls have been arrested on suspicion of manslaughter".
Detective Superintendent Phil Owen said: "We are working with our colleagues from the fire service to establish how this fire, which has tragically claimed the life of a fire fighter, started.
"We have already arrested two juveniles in connection with the fire and our enquiries are continuing.
"If anyone has any information about how the fire started please get in touch."
Today Mr Hunt's shattered family were coming to terms with his death and were described as being ''absolutely grief-stricken''.
County Fire Officer for Greater Manchester Fire and Rescue Service, Steve McGuirk, said: ''We are devastated by the loss of one of our colleagues who has died in the line of duty.''
Mr McGuirk said Mr Hunt is thought to have been enveloped by some kind of ''super heat''.
He added: ''At the minute it's really too early to say what's led to the firefighter's death. It doesn't look like a building collapse or that he fell through any floors. The early indications are an absolutely massive, ferocious and sudden build-up of heat.
''But where that came from and what caused that we have got absolutely no idea at this stage. That's really the purpose of the investigation that we are now engaged in.''
Mr McGuirk said he could not rule out that the sudden intense heat may have been generated by steam or chemicals from inside the hair salon.
He said: ''We never expect to lose a colleague in this way and it brings home the dangers that our firefighters put themselves in every day to keep the community safe.
''Stephen had been a dedicated firefighter since 2008 and we are all in a state of shock.
''It is a very sad day for Greater Manchester Fire and Rescue Service and all our thoughts are with Stephen's family and friends.''
The fire began around 2.50pm yesterday and is still being dealt with.
Details of exactly what happened are unclear but an investigation into the cause of the fire has been launched.
Arson is not being ruled out.
Mr McGuirk said that fire crews thought they were starting to get the blaze under control by about 8.30pm last night but for some reason, which they do not have an explanation for yet, a ''BA emergency'' was declared - which is a signal for everybody to evacuate the building.
''When that took place two firefighters were pulled from the building by their colleagues, very seriously injured,'' said Mr McGuirk.
Paramedics treated the firefighters at the scene and took them to hospital but Mr Hunt was declared dead when he arrived at hospital just a few minutes later.
The other firefighter is not critically injured.
''We are really now trying to understand what happened and what led to this awful tragedy.''
The chief fire officer said Mr Hunt had two teenage children and that his family were ''absolutely grief-stricken'' and said it was still a ''very raw situation''.
Mr McGuirk, who has been in the fire service for over 35 years, said everyone was in ''deep shock''.
''I don't think I have ever seen as much shock and sheer devastation on people's faces,'' he said.
He said that during the night's de-brief peoples' eyes were ''glazed over'' as they began to understand what had happened.
''The suddenness of what happened really took everybody by surprise so it is really important that we do understand what happened because it was something extraordinary and out of step with the way the incident was proceeding,'' he said.
He added: ''The firefighters are clearly devastated by the loss of their colleague and I pay tribute to their professionalism, courage and dedication - while in mourning they are continuing to keep the community safe.''
Neighbouring fire and rescue services have started an investigation into the incident and circumstances leading to the tragedy alongside Greater Manchester Police GMP.
A spokesman for the Chief Fire Officers Association said: ''We are all devastated by the news of the tragic loss of Firefighter Stephen Hunt who has been killed in the line of duty.
''The Chief Fire Officers Association have offered its full support to Chief Fire Officer Steve McGuirk at what are the most difficult of times for Greater Manchester Fire and Rescue Service. Colleagues from neighbouring services are currently providing direct support and we will remain ready to help in whatever way we can.
''We offer our sincere condolences to Stephen's family, friends and colleagues at this very sad time.''
Matt Wrack, General Secretary of the Fire Brigades Union, said: "This is a terrible tragedy. Firefighters in Greater Manchester and around the UK are devastated by the news. The thoughts of everyone in the fire and rescue service will be Stephen's family, friends and colleagues at this time.
"This terrible incident will now need to be thoroughly investigated and we are putting those arrangements in place. That will draw on experience and expertise from around the country to ensure the process is followed carefully and methodically."
Mr Wrack will be visiting Manchester today to look at the scene of the incident and to speak to firefighters and Fire Brigades Union officials regards the arrangements which need putting in place.
Floral tributes were left at the scene at the corner of Tib Street and Church Street.
One tribute read: "All our thoughts are with our fallen colleague, his family and friends. RIP. Redwatch Sale."
Another read: "To a brave man who was only doing his job. Rest In Peace."
The manageress of the business where the fire started, Nicola Purcell, arrived at the scene along with other staff members to lay flowers in tribute to the fallen firefighter.
She said that they along with business owner, Paul Barnett, fought the blaze when it first started with fire extinguishers and water.
She also said an off-duty fire officer came to their aid.
Ms Purcell said Mr Barnett stayed to fight the fire until he was removed from the scene by firefighters and that he was taken to Manchester Royal Infirmary with smoke inhalation and minor burns.
She said he was released from hospital last night but because of his condition he was not able to come to the scene today.
The business is a supplier of hair extensions and hair beauty products.
Almost 20 members of staff arrived to pay their respects.
The group stood and watched while a police officer placed their bouquets of flowers with the other floral tributes.
Some held on to each other for support and other members of the group wept from the emotion of the day.