Glasgow's subway will close for four weeks from Saturday to allow modernisation works to take place.
Glasgow Art School Badly Damaged
Firefighters are tackling a major blaze at Glasgow School of Art in the city centre.
The fire at the Charles Rennie Mackintosh building was reported at about 12.30pm.
It's understood it started in the basement and spread up through five floors, setting the roof on fire.
Senior firefighters said the operation at the scene was likely to be "protracted''.
While there are no reports of anybody having been injured, the fire service confirmed that it did lead several people to safety.
In its latest update, the fire service said crews remain in attendance and have been working to bring the fire under control with high pressure water jets.
A spokesman said: "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, who is at the scene, 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 under way.''
Mr Hay said: "At this point we can't establish what the cause is but we have specialist teams working with Police Scotland to establish the cause.
"We've had a significant fire within the building and at this point we're still extinguishing that fire. We've had firefighters inside working under very arduous conditions and at a later point we'll be able to determine and describe the conditions more fully.
"There has been significant spread within the building but we've used all our resources to bear on it.
"We regularly attend significant fires but the iconic status of this building is not lost on us.''
He said there were 17 units from Glasgow at the scene and specialist units from across the country.
"Part of our operation is to try and salvage what we can and we worked with colleagues from the school who identifyied objects of significance that they would like us, if possible, to save.
"They described the objects and their location and we briefed officers and firefighters, where they could, did the salvage if it was safe to do so.''
He could not say what objects were saved.
When asked if all student work has been destroyed he said: "It's too early to establish that. There was a salvage plan and we've worked to save the iconic items but we're not unaware of the importance of the work of students within that building.
"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.''
Muriel Gray, chair of the board of governors at the school: "It's been an absolutely devastating day for everyone involved with the School of Art, students who are preparing for their degree show and all the staff.
"We just want to make it clear that we are so grateful to the fire service who responded within four minutes and there were no casualties which is the main thing that we were concerned about.
"It's a very black day and we have a lot things to do and think about now.
"We are waiting for the investigation to be completed then we can start to rebuild some of the things that need done.
"Our thoughts are of course with the students whose degree shows were being prepared but I would like to say I have never been prouder in my life of an art school because the staff and students and the people of Glasgow have been fantastic.
"We don't know what's been destroyed and what's been salvaged so we're just waiting for the all clear so that we can get in and assess the damage. It's just a waiting game.''
Devastated students say today is deadline day for their degree submissions, and many standing in the street have been in tears.
Hugh Thornhill, a second year student, said: "I was helping one of the fourth years set up their exhibit and suddenly the alarm went off. We didn't think it was anything but we had to go out and then we saw smoke coming out and realised that it was really bad.
"It got to the point where flames were coming out of the top floor.
"All that effort is gone, everyone's work on that side of the building is ruined. Even if it didn't catch fire it will be damaged extensively.
"The degree show next month is pretty much a bust now, it's sad.''
The Scottish Fire and Rescue Service said four appliances were sent from Cowcaddens, Yorkhill and Maryhill fire stations, and firefighters were on scene within four minutes.
The Art School has tweeted (@GSofA) to say that everyone is safely out of the building, and to thank everyone who has expressed concern.
Staff are arranging for locksmiths and services for students who left personal belongings and keys in the building.
Second year student Clare Reilly said: "It's not about that (keys and personal belongings), four years of work is gone for all those students, the deadline was at 5pm today.
"Even the archive and library in there will be gone.
"There's so much work and history in the building and it's gone. I've got two years to go but we might not be allowed back in.''
Glasgow School of Art has produced a host of famous alumni across the creative fields over the past 165 years.
As well as renowned artists, former students include members of the bands Travis and Franz Ferdinand, and actors Peter Capaldi and Robbie Coltrane.
Several winners of the prestigious Turner Prize studied at Glasgow School of Art (GSA), including Martin Boyce, who scooped the prize in 2011 for his installation Do Words Have Voices, beating what critics felt was the strongest shortlist for many years.
Graduate Douglas Gordon took the prize in 1996 while it was won by Richard Wright in 2009. Simon Starling also picked up the accolade in 2005.
This year three out of the four candidates for the UK's best-known art award - worth #25,000 - studied at the school.
Dublin-born film-maker Duncan Campbell, 41, has been nominated for his presentation It For Others, described as a reflection on a 1950s documentary about African art.
He studied in Belfast before completing the Master of Fine Art (MFA) programme at Glasgow in 1998 and continues to live and work in the city.
Canadian Ciara Phillips, 37, is a Glasgow-based screen printer shortlisted for a project where she set up a temporary studio and invited artists, designers, and local women's groups to produce new screen prints. She also completed an MFA at the School of Art in 2004.
Tris Vonna-Michell, 31, was born in Southend-on-Sea and graduated from Glasgow in 2005.
Other famous artistic alumni include Alasdair Gray, writer of Lanark, who is also known for his murals around Glasgow in locations such as Oran Mor and the Ubiquitous Chip, and artists Joan Eardley and Peter Howson.
Artist and playwright John Byrne, former partner of actress Tilda Swinton, also studied at GSA, as did poet and playwright Liz Lochhead and Labour politician Cathy Jamieson MSP.
In the music world, Fran Healy, Dougie Payne and Andy Dunlop from Travis and Robert Hardy from Franz Ferdinand are among the school's alumni.
David Shrigley, nominated for the Turner Prize in 2013, studied at GSA, as did Jenny Saville, who exhibited in the Royal Academy's Sensation exhibition in London in 1997, and Alison Watt, the first woman to have a solo exhibition at the Scottish National Gallery.
Charles Rennie Mackintosh himself studied at GSA where he met his wife Margaret MacDonald.
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