Today's tragic developing story is the massive fire engulfing the historic Glasgow School of Art building, the masterpiece by Scottish architect Charles Rennie Mackintosh.

News updates and tweets (#gsafire) are pouring in left and right, and we'll try to collect the latest developments in this post.

Tweets about "#gsafire"

The Glasgow School of Art Media Centre tweets a link to this Statement from Muriel Gray, Chair of Board of Governors on fire at the Mack:

"Today is a really black one for the GSA, but I cannot thank the fire brigade enough for the speed with which they came and their commitment to contain and extinguish the fire.  

Fortunately there have been no fatalities or injuries. 

I am so proud of the staff and students and how everyone has pulled together. We are thankful to all the Glaswegians who turned up to comfort students and to friends from across the world for their messages of support."

The Scottish Fire and Rescue Service publishes this update:

Fire at the Mackintosh Building in Glasgow - UPDATE 4.00 pm, Friday 23 May 2014

Firefighters remain in attendance at the scene at the Mackintosh Building in Glasgow.

SFRS crews have been working to bring the fire under control with high pressure water jets used to douse the flames.

Appliances from across Glasgow and west Central Scotland were mobilised to the incident, which began shortly before 12.30pm.

Firefighters reached the scene within four minutes of the service receiving the first of several 999 calls.

Search and rescue teams entered the building wearing breathing apparatus and led a number of people to safety.

Both internal and external firefighting operations have been conducted throughout the incident and three aerial rescue pumps are currently being used to douse the flames from height.

There are no reports of injuries at this point.

Chief Officer Alasdair Hay is in attendance. He said: "This is likely to be a protracted incident and crews have been working extremely hard to tackle what is clearly a very significant fire.

"The priority throughout this operation has been to protect life but salvage operations are also underway."

There is no further information at this time.

Latest update to Glasgow School of Art's Wikipedia entry:

The original Mackintosh building was severely damaged by fire on 23 May 2014. The extent of the damage and future of the building has still to be determined.

The fire which began in the basement quickly spread upwards and although brought under control quite quickly, significant damage was done to the historic studios, stairways, and the renowned Mackintosh library. There were no reported casualties.

The fire broke out as students were preparing for their Degree Show. Eyewitnesses said the fire appeared to have started when a projector exploded in the basement of the Charles Rennie Mackintosh building just before 12:30.

A heartbreaking picture tweeted by @CraftFestival shows the extend of the blaze that initially started in the building's basement:

Out hearts go out to everyone @GSofA I am an alumni. Tragic and at degree show time. Take care everyone #gsafire

Stephen Hodder, President of the Royal Institute of British Architects (RIBA), says in a statement:

“The most important work by Charles Rennie Mackintosh, an architect of international significance, Glasgow School of Art is held in the highest regard by architects and the public alike - it was rightly judged to be the best building of the past 175 years, in a nationwide poll run by the Royal Institute of British Architects.

“Damage to a building of such immense significance and uniqueness is an international tragedy. It is irreplaceable.

“The RIBA joins our colleagues in Scotland in sending out a message to the students, staff of the School and all those who have been associated with this building over the decades, a message of sorrow and commiseration at this terrible, terrible news. It is too early to talk about what happens now, but the Institute will do anything it can to help in any way.”

The President of the Royal Incorporation of Architects in Scotland, Iain Connelly, comments on today's events:

"The value of this building goes well beyond Glasgow or even Scotland. It is a work of architectural heritage of world renown and its influence on 20th century architecture is immeasurable. Scotland has seen the loss of an international treasure which reflects the genius of one of our greatest ever architects and the whole of the architectural profession in Scotland will, I am sure, join with me in sending out a message to the students and staff of the School and all those who have been associated with this building over the decades, a message of sorrow and commiseration at this terrible, terrible news. It is too early to talk about what happens now, but the architectural profession in Scotland will do anything it can to help in any way."

Hopes that Mackintosh's art nouveau library may have survived the flames are getting slimmer:

It's believed the Mackintosh library has been lost in the fire. - @_AndyYoung

STV Glasgow reports that the main fire has been extinguished by the fire crew:

Chief officer Alasdair Hay said: "There are still pockets of fire but we are confident we have extinguished the main fire. There are structural engineers here and we are working with them to save as much of the fabric as we possibly can."

Hugh Pearman, editor of the Royal Institute of British Architects Journal, remarks:

Today's destruction proves one thing: if so many people feel bereaved by the loss of a building, then it can be said to have had a soul.