A fire which has ravaged Glasgow's School of Art and its historic Mackintosh Building has spread to "several properties" including the O2 ABC music venue.

Buildings including the O2 ABC and Campus nightclub have suffered "extensive damage" as flames and smoke poured into the night sky from the Glasgow School of Art (GSA) building.

HeraldScotland:

The inferno broke at 11.20pm on Friday at the college, which had recently undergone a multi-million pound restoration project backed by Brad Pitt following a fire in 2014.

Efforts to bring the fires under control were expected to be "prolonged", Deputy Chief Officer Iain Bushell said.

It is understood fire crews arrived to find around 50% of the building already engulfed in flames.

More than 150 firefighters were dealing with "an extremely challenging and complex incident", Mr Bushell added.

A total of 50 firefighters remained on the scene on Saturday morning in the wake of the blaze. They are expected to be at the scene for days

Scottish Fire and Rescue Service deputy assistant Peter Heath said "pockets of fire" remained, but were under control.

The School of Art building had been "extensively damaged" and  all floors were affected.

One Twitter user posted a video which appeared to show the O2's roof  collapse

O2 ABC tweeted: "Just to let you know everyone is safe and was evacuated in time. Sending much love to our friends at @GSofA, we are absolutely gutted. Regarding events, our O2 ABC2 gig + club will not be going ahead tonight. We will update asap on the rest of the programme. x."

Hundreds evacuated their homes and watched the drama unfold from the street, as the fire spread.

Firefighters pumped water from the River Clyde to tackle the blaze, resulting in road closures.

An area in and around Sauchiehall Street just half a mile from the inferno is still recovering from a massive blaze that hit Victoria's nightclub three months ago.

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 the devastating fire in 2014.

HeraldScotland:

Pictures by Kirsty Anderson.

Scottish Secretary David Mundell said the Government "stands ready to help" the Glasgow School of Art "financially or otherwise"

More than 120 firefighters were called to tackle the blaze at just before 11.20pm on Friday night.

There are no reports of casualties, although residents living nearby have been evacuated from their homes.

HeraldScotland:

Deputy Chief Officer Iain Bushell said: "This is an extremely challenging and complex incident, but the response and professionalism of our firefighters has been exceptional.

"The fire has taken hold several properties including the 02 ABC nightclub causing extensive damage.

"This will be a prolonged incident and crews will remain on the scene as they work to prevent further fire spread and damage."

Rachael Docherty, 29, is a former graduate of the art school and told the Press Association: "This is terrible. This is a lot worse than the last one.

"We were out earlier on and at 12am we came out it just looked like (it was) fireworks and now it's just white smoke.

"The Mac building is a piece of Glasgow history, it's not art school history, it's Glasgow."

John McInnes, 22, said: "I can't believe that this has happened again to such an iconic building. It's unbelievable.

"Questions need to be asked, they spent so much on renovation, but this seems so much worse than the last one."

Fire took hold of the Glasgow School of Art building in May 2014 in the run-up to the students' degree show, and graduation ceremonies had taken place at the institution earlier on Friday.

HeraldScotland:

The fire at the building, which was designed by artist and architect Charles Rennie Mackintosh and built between 1897 and 1909, has been called "devastating" by the city council leader Susan Aitken.

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.”

Paul Sweeney, shadow Scotland minister, said the Mackintosh Building was the "most architecturally important building" in the city.

He added: "Oh dear, the 1909 library extension, that was the origin of the 2014 blaze is now fully alight too. It looks like the entire interior space is now fully alight.

"The best we can probably hope for is structural facade retention and a complete rebuild of the interior. Devastating.

"There must be a comprehensive national effort to ensure every possible option to salvage and restore what is one of the finest edifices in the history of world architecture is pursued in the wake of this latest setback.

"I'll be doing everything I can to promote that in Parliament."

Mr Mundell tweeted that he was "devastated to hear news of fire at Glasgow School of Art".

"Only fortnight since I was there to see restoration