Denmark’s historic old stock exchange building in the centre of Copenhagen has been engulfed by fire.

The 17th Century Børsen is one of the city’s oldest buildings and onlookers gasped as its iconic dragon spire tumbled into the street below.

Culture minister Jakob Engel-Schmidt said 400 years of Danish cultural heritage had gone up in flames.

Members of the public rushed to rescue historic paintings and it took hours before the fire was under control.

The building, dating back to 1625, is a stone’s throw from Denmark’s parliament, the Folketing, housed in the old royal palace of Christiansborg castle. Danish media said the nearby square was being evacuated and the main entrance to Christiansborg was closed because of smoke.

The old stock exchange was being renovated and had been shrouded in scaffolding and protective plastic covering.

It currently houses the Danish chamber of commerce, which described the scenes on Tuesday morning as a terrible sight. Its director, Brian Mikkelsen, said as much as half of the old stock exchange had burned down but vowed that it would be rebuilt “no matter what”.

Local craftsman Henrik Grage told Danish TV that it was a tragic day. “This is our Notre-Dame,” he said, comparing it with the fire that engulfed the roof and spire of the cathedral in the centre of Paris almost exactly five years ago.

The Paris fire broke out under the eaves of Notre-Dame on 15 April 2019 when it was also shrouded in scaffolding as part of extensive renovations. Investigators have blamed either a short circuit in the electrics or a worker’s cigarette butt that was not properly put out.

The cause of the fire in Copenhagen is also for the moment unknown but emergency services said the scaffolding made their operation more difficult. Officials said the fire was most intense around the tower.

One of the craftsmen replacing brickwork on the building saw the fire break out on the roof while he was on the scaffolding. Ole Hansen said he shouted to his colleagues they needed to get down and that he left the door unlocked for firemen to get in.

Fire department chief Jakob Vedsted Andersen said firefighters faced an almost impossible task accessing the area under the old copper roof. It was not until Tuesday afternoon that he said the fire had been brought under control.

“I’m completely speechless – this is an unparalleled tragedy,” one onlooker told Danish media.

Members of the public joined emergency services as well as the head of the chamber of commerce in rushing into the building to save the Børsen building’s substantial art collection.

Prime Minister Mette Frederiksen spoke of “terrible images” and of a piece of Danish history going up in flames.

Local museum inspector Benjamin Asmussen told Denmark’s TV2 that the fire was difficult to watch, as the old stock exchange was filled with paintings of Danes who had played important roles since the 17th Century.

Camilla Jul Bastholm from Denmark’s National Museum said that several hundred works had been rescued and taken into storage under escort. Among the prized works rescued was an 1895 portrait by PS Krøyer of 50 Danish men of commerce standing inside the building in their top hats. Ornate chandeliers, mirrors and some clocks were also recovered.

King Frederik X said the fire was a “sad sight” for such an important part of Denmark’s cultural heritage: its characteristic dragon spire had helped define Copenhagen. He succeeded Queen Margrethe II in January and events for her 84th birthday planned on Tuesday were being toned down because of the fire.

The Dutch Renaissance-style building on the city’s Slotsholmen, or palace island, was commissioned by Denmark’s King Christian IV with the aim of turning Copenhagen into a major trading centre.

The famous spire featured four dragons whose tails were twisted into a spear and three crowns, symbolising close ties with neighbours Norway and Sweden.