COPENHAGEN, Denmark — A fire raged through one of Copenhagen’s oldest buildings Tuesday, causing the collapse of the iconic spire of the 17th-century Old Stock Exchange as passersby rushed to help emergency services save priceless paintings and other valuables.

The blaze broke out on the building’s copper roof during renovations, and police said it was too early to say what caused it. The building with its distinctive 184-foot spire in the shape of four intertwined dragon tails has been a major tourist attraction next to Denmark’s parliament, Christiansborg Palace, in the heart of the capital.

“A piece of Danish history is on fire,” Prime Minister Mette Frederiksen wrote on Instagram, saying that it hurt to see the loss of such “irreplaceable cultural heritage.”

Ambulances were at the scene but there were no reports of casualties.

Danish Culture Minister Jakob Engel-Schmidt said it was “touching” to see how many people lent their hand “to save art treasures and iconic images from the burning building.” One man jumped off his bicycle on his way to work to help during an initial period before firefighters cleared people from the building.

Brian Mikkelsen, chief of the Danish Chamber of Commerce, which is headquartered in the Old Stock Exchange and owns the building, was seen with his staff scrolling through a binder of photos of paintings to be saved. Works were carried to the nearby parliament and national archive building. Rescuers used tools such as crowbars to remove valuables to save them from the fire, Mikkelsen said.

“We have been able to rescue a lot,” a visibly moved Mikkelsen told reporters. “It is a national disaster.”

The fire began on the roof Tuesday morning and spread to much of the building, collapsing parts of the roof and destroying about half of the building, firefighters spokesman Jakob Vedsted Andersen said. There was no risk to other buildings, but it was expected to take firefighters 24 hours to secure the scene, he said.

Tim Ole Simonsen, another spokesman for the Greater Copenhagen Fire Department, said “the fire started in the part of the building where work has been going on, but that’s all I can say about it.”

René Hansen of the coppersmith company that was renovating the roof told broadcaster TV2 it had 10 people on the roof when the fire alarm went off. “After five minutes, smoke began to rise from the floor to the ceiling.”

Tommy Laursen of the Copenhagen police said it was too early to say what caused the fire and that police would able to enter the building in “a few days.”

Firefighters who reportedly pumped water from the nearby canal were seen spraying water through the doorway of the Old Stock Exchange’s gilded hall that is used for gala dinners, conferences and other events and where many paintings hung.

Huge billows of smoke rose over downtown Copenhagen and could be seen from southern Sweden, which is separated by a narrow waterway.

Up to 90 members of an army unit were deployed from a nearby base to cordon off the area and “secure valuables,” Denmark’s armed forces said.

King Frederik wrote on Instagram that “an important part of our architectural heritage” was being destroyed. “This morning we woke up to a sad sight,” he wrote.

The exchange was built in 1615 and considered a leading example of Dutch Renaissance style in Denmark. The Chamber of Commerce moved into the building after Copenhagen’s stock exchange left in 1974.

The roof, masonry, sandstone and spire were being renovated, and Mikkelsen said there were plans to have the royal family, government officials and other dignitaries review the work later this year. “That won’t happen now,” he said.

It was unclear what will happen to the iconic building.

Engel-Schmidt, the culture minister, wrote on X that “I will do everything I can so that the dragon spire will once again tower over Copenhagen,” and said it had been “a symbol of Denmark’s strong history as a trading nation.”

The adjacent Christiansborg Palace has burned down on several occasions, and most recently in 1990 a fire broke out in an annex of the Danish parliament, known as Proviantgaarden. However, the Old Stock Exchange was unscathed at the time.

Police said on the social media platform X that a main road in Copenhagen was closed and people should expect the area to be cordoned off for some time. Several bus lines were rerouted and Danish media reported huge traffic jams.

Queen Margrethe, who turned 84 Tuesday, toned down the celebrations because of the fire, broadcaster TV2 said. A band with the Royal Life Guard was to play for the former monarch outside the Fredensborg Castle, where she is staying for the spring and summer, but that was canceled.