Residents have reacted in shock after flames ripped through a £20m science building at the University of Nottingham.
Firefighters are dampening down this morning and waiting to investigate the cause of the blaze.
Sixty fire fighters from crews across the county attended the scene last night.
Carolyn Wilkinson, 41, of Charnock Avenue, Lenton, could see the drama unfolding from her home.
She said: "It was at about quarter to ten I was first alerted to it. I had a loft conversion and looked out the sky light. At first I thought my neighbour had a log fire. There were massive bangs."
"We went to bed about quarter past midnight. It was still ablaze but the roof had gone. The building had disappeared.
"It was horrible and it's very sad. I hope it wasn't deliberate."
Ray Sharpe, 79, Wollaton, was on a morning bike ride when he passed by the scene on Saturday morning.
He said: "When we got in I heard it on the radio. It's certainly a disaster."
Jean Dunhan, 69, and David Fallows, 69, who live together at nearby Churchfield Lane, in Radford, also witnessed the blaze.
Mrs Dunhan said: "My son phoned me yesterday evening to say he had seen it on the internet. I didn't know anything before that.
We walk around here regularly and we've seen the building being built.
Mr Fallows added: "I looked out of the back garden window looking out onto the university. I could see flames and sparks. It was just like fireworks going off.
"We went outside out at about 10pm to The Plough pub which is even closer.
"I can't believe what was there before and what is there now. All the workers, all those jobs and money – it's a shame."
Newark fire station manager Seth Armstrong attended the scene on Saturday morning.
He said: "It's a very serious incident. I got here about 3am. The first responsibility was to check all the peripheral buildings. We're now at the stage where we're can go in there and help with the situation. Because it's a timber base, four or five secondary fires were around the scene. There were 12 fire engines and an average of five firefighters per engine.
"We're now trying to ramp it up and going in aggressively and get into the fire site. It will be at least 24 or 26 hours before we can make that massive difference.
"The investigation will follow. It's not safe enough to go in there yet.
"There are lots of pits, shafts and ladders that make it unsafe to go on the site."
According to Mr Armstrong, the cause was still unknown.
The fire is believed to have broken out at 8.45am on Friday, September 12.
The building, empty and still under construction, was part-funded by a £12m donation from pharmaceutical giant GlaxoSmithKline.
The University of Nottingham has said it will still continue with a planned open day and badminton competition despite the incident.
Senior Security Officer at University of Nottingham Steve Garrod said:
"I got called back again to work prior to 9pm. The cause of the fire is still under investigation. The firefighters are just dampening down. It's business as usual. The open day is still going ahead and so is the badminton competition.
"We are going to conduct an investigation into the building opposite. Once it was opened, running it was going to cost nothing to run because it's made out of sustainable sources.
"We are trying to open the surrounding businesses as well."
A spokesperson for Morgan Sindall, the main contractors for the building said: "Everyone on the project team has been working hard to deliver this state-of-the-art low carbon laboratory for the University and we are of course greatly saddened to see the devastation caused by the fire.
"We are supporting the fire service investigation into the cause of the incident and thank its officers for their efforts last night to tackle and contain the blaze."
