A major fire has torn through one of Scotlands architectural gems, the Mackintosh building at the Glasgow School of Art, following another blaze four years ago. More than 120 firefighters fought the flames during the night as it gutted the 1909 building and spread to a theater and a nearby night club. There were no casualties, the fire service said. "The extent of the damage is very severe," Peter Heath, deputy assistant chief officer of the Scottish Fire and Rescue Service, told reporters at the scene in Glasgow city center on Saturday morning. He said the fire had "reached from the ground floor right through to the roof". The Mackintosh building had been due to re-open next year after millions of pounds in restoration works following a fire in May 2014. "This is a devastating loss for Glasgow, absolutely devastating," Heath said. He said it was too soon to determine the cause of the fire, which would be investigated by multiple agencies. The fire was first reported at about 20 minutes before midnight on Friday. By morning the fire was under control, but smoke was still rising from the building as firefighters sprayed it from tall ladders. Eyewitnesses told the BBC the fire looked "much worse" than the last one.