FIRE has caused "extensive" damage at Glasgow's famed Mackintosh Building and hit multimillion-pound restoration work carried out in the aftermath of a previous blaze, a fire officer has confirmed.

Scottish Fire and Rescue Service deputy assistant chief officer Peter Heath said the Glasgow School of Art building had been "extensively damaged by fire" that had "spread very rapidly".

Crews were called to the building in the city centre at around 11.20pm on Friday and were met with "extremely difficult conditions", he said.

Less than an hour later, flames and smoke were belching into the night sky – with more than 150 firefighters eventually deployed at the scene.

"[The fire] reached from the ground floor right through to the roof. It is significantly damaged," Mr Heath said.

The National:

Photograph: Kirsty Anderson

The fire spread to nearby buildings, including the O2 ABC music venue – although firefighters managed to prevent it taking hold any further.

Despite the scale of the blaze, no casualties have been reported.

A restoration project, which was set to cost between £20 million and £35 million, had been returning the famous art school to its former glory after a devastating fire in 2014, with Brad Pitt and Peter Capaldi among those lending their support.

Asked if any of the restoration work had been destroyed, Heath replied: "I would say, given the extent of the fire, that would be a fair comment."

The fire officer said the blaze was a "devastating loss for Glasgow", with firefighters dealing with a "sense of loss" along with the city's people.

Crews are remaining at the scene to dampen down pockets of fire at the Mackintosh Building and the O2 ABC.

Responding to the fire, First Minister Nicola Sturgeon said: “This is a very sad morning in the city of Glasgow. Glasgow School of Art is an institution that is loved not just by its students, staff and the people of this city, but by many around the world.

“First and foremost my thoughts are for the safety of people. At this stage it appears there are no casualties and I hope that continues to be the case.

“The professionalism and bravery of the Fire Service, and the rest of the emergency services, was once again demonstrated last night. This is clearly an extremely complex and large-scale incident, and one that is on-going. I would like to thank the emergency services for their continued efforts.

“The Scottish Government stands ready to provide any support that may be required, now and in the period ahead. I have been receiving regular updates and will continue to do so throughout the day. The Scottish Government’s resilience room was activated overnight and will provide any support necessary.”

Scotland Secretary David Mundell also pledged that support would be available from the UK Government.

He tweeted: "Devastated to hear news of fire at Glasgow School of Art. Only fortnight since I was there to see restoration. My heart goes out to all those who had worked so hard on that. @UKGovScotland stands ready to help, financially or otherwise @GSofA"

The blaze which tore through building in 2014 began when a projector ignited gases from expanding foam used in a student project, a fire investigation confirmed.

The flammable gases from a foam canister caught fire when they came into contact with the electrical equipment as work was being carried out on a nearby art installation.

The projector was not faulty, but the presence of original ventilation ducts and a large number of timber-lined walls in the building contributed to the rapid spread of the fire, the report concluded when it was published in November 2014.

A new fire suppression system was in the latter stages of completion at the institution, but was not yet fully commissioned and working on the day of the blaze.

Speaking at the time, the GSA director Professor Tom Inns said: "The fire was an accident and, like any accident, it's caused by many different factors coming together and conspiring against us on the day.

"The report is very detailed about how the fire spread round the building and that gives us a lot of new knowledge that we need to take on board."