Sixty firefighters are tackling a large blaze at the University of Nottingham.
The fire started in the GlaxoSmithKline (GSK) building on Triumph Road, Radford, which was under construction.
Nottinghamshire Fire and Rescue tweeted: "Help our crews by staying away from the Triumph Rd area & close doors & windows if you're local - flying debris making conditions difficult."
It said the blaze was "significant" but that no casualties had been reported.
Nottinghamshire Fire and Rescue Service said it was called out at about 20:35 BST.
A spokesman said: "The building was under construction, it was not in use and was about 70% complete. We have around 60 firefighters on the ground and using aerial platforms.
"We are likely to be here for some time into the morning."
Steve Beech from Radio Nottingham, at the scene, said: "I can see embers falling from what is a chemistry laboratory that's being built.
"It's being funded by GlaxoSmithKline on the Jubilee Campus in Nottingham.
"There's a huge elevated jet squirting water. Hundreds of people have come out to see it.
"There's a huge plume of smoke above Nottingham this evening."
Dr Paul Greatrix, registrar at the university, said: "Firefighters are currently on site dealing with a major fire at our GSK sustainable chemistry building on Jubilee Campus.
"Thankfully, there have been no casualties as this is a building that was still under construction.
"Our number one priority is to ensure that the fire does not spread to other buildings in the vicinity and we are grateful to the fire teams on site who have worked extremely hard to contain the blaze."
He said the university's open day on Saturday would go ahead as planned.
Pictures of the blaze have been posted on Twitter.
David Wilson tweeted: "Just driven past Nottingham University fire. Horrendous scenes, not quickly forgotten."
Sarah Armes said: "So sad to see the lovely Eco building in flames."
Kirsty tweeted: "Nottingham uni is completely on fire! Just drove past it there's an entire building destroyed."