COPENHAGEN, Denmark (AP) — Firefighters in Copenhagen plan to start taking down scaffolding that is left dangling dangerously Friday outside the ruins of the Danish capital’s historic Old Stock Exchange building after a fire tore through it and collapsed much of its structure.

A large blaze broke out at the 400-year-old landmark on Tuesday, toppling its roof and iconic dragon-tail spire. On Thursday, a large section of the outer wall of the building collapsed inwards. The most valuable paintings and items inside had been saved from the flames, and no one was injured.

“Right now, structural engineers and engineers are assessing how it can be done to cut the scaffolding free,” said Tim Ole Simonsen, a spokesman for the Greater Copenhagen Fire Department. “It is very difficult work.”

He added there were still pockets of small fires and “tons” of debris inside the ruins of the building, which dates to 1615 He said they were also using a drone to survey the work.