FIREFIGHTERS surveyed the scale of the damage to the world-renowned Glasgow School of Art three days after it was devastated by a massive blaze.

As dramatic images surfaced on Monday of the blighted west wing of the Mackintosh building, that housed the stunning library, fire chiefs said they were confident they would discover how the blaze started - but stressed the “very complex” investigation would take time.

READ MORE: The Glasgow School of Art damage is dire - but the ABC is important too

At the height of the incident late on Friday night, more than 120 firefighters were involved in fighting the flames.

Glasgow Times:
The world-famous library in the Mackintosh building (Colin Mearns)

There have been no reports of any casualties.

A few pockets of fire remained which crews were still working to extinguish on Monday.

Firefighters also took to the roof of the Reid building - opposite “the Mack” - where the glass panels shattered from the ferocity of the blaze.

Small crowds of people stood on Renfrew Street staring in silence at the east wing of the Mack which has become a hollow, charred-out shell.

READ MORE: O2 ABC breaks silence after popular music venue is devastated in Art School fire

The north end of Sauchiehall Street remained closed to pedestrians and traffic as around 20 businesses remained shut.

The scale of the damage to the roofs of Campus and the O2 ABC were also laid bare as pictures showed they had completely caved in.

The blaze shocked and saddened people in Glasgow and beyond including leading figures in the worlds of art and music.

Glasgow Times:
Archaeologist Edward Rayner in the devastated library after May 2014’s fire (Colin Mearns)

Singer Annie Lennox tweeted: “So sad and disappointed for everyone affected by this 2nd devastating fire... (who would believe??!!) at Glasgow’s historic and renowned Charles Rennie Mackintosh art school. .. the renovators, students, staff, alumni, noble fire fighters and everyone in Glasgow.”

READ MORE: Roads to remain closed after Glasgow School of Art fire

Experts estimated the cost of rebuilding the gutted Mackintosh would be at least £100 million, if anything can be salvaged at all.

However, the school’s bosses said they remained hopeful of a positive outcome.