A devastating fire ripping through the historic Notre Dame Cathedral in Paris has destroyed the cathedral’s spire, which weighs an estimated 750 tons, and caused the ceiling to topple. There are fears that the stained glass windows will melt amid the heat.

“Our lady of Paris is in flames,” French president Emmanuel Macron said in a statement on Monday evening. The church is the most visited site in Europe.

The blaze was hard to contain in part due to its remote location on Île de la Cité in the Seine river, which has made it difficult to access with hoses. And while officials were unsure for hours if they would be able to contain the blaze at all, a representative for the firefighting team told Reuters just before 11 p.m. Paris time that the structure would be saved from “total destruction.”

The fire reportedly broke out in the bell tower, which has been the site of an extensive, ongoing $6.8 million renovation project.

“Everything is burning, nothing will remain from the frame,” Notre Dame spokesman Andre Finot told the AP on Monday evening. The city’s deputy mayor said that first responders were working to salvage artwork and other objects from inside the church. No deaths have been reported, although one firefighter is reportedly “seriously injured.”

The fire alarm first went off around 6:30 p.m. local time, according to media reports.

Paris mayor Anne Hidalgo confirmed on Twitter within an hour of the first alarm that “a terrible fire” had broken out and that firefighters were working to halt the flames. The area around the church was swiftly evacuated. “I ask everyone to respect the security boundaries,” Hidalgo said.

The news quickly spread on social media as Twitter users began uploading videos of smoke clouds billowing from the Gothic spires of the building, which welcomes an estimated 13 million visitors a year, or approximately 30,000 each day.

Outside the evacuation zone, onlookers gathered to weep, sing hymns, and pray as they watched the flames.

Emmanuel Macron, who had planned to address the nation on Monday evening about the ongoing Yellow Vest protest movement, postponed his speech following news of the blaze. He plans to visit the site of the fire instead.

The original Notre-Dame spire was built in the 13th century, but was recreated in the 19th century by architect Eugène Viollet-le-Duc. The new version, now destroyed, was made of oak covered with lead. The spire was surrounded by 16 copper statues of the Apostles, which had recently been removed to accommodate the restoration work and are believed to be safe.

Smoke and flames rise during a fire at the landmark Notre-Dame Cathedral in central Paris on April 15, 2019, potentially involving renovation works being carried out at the site, the fire service said. (Photo by FRANCOIS GUILLOT / AFP / Getty Images.)

A rooster at the top of the spire contained three relics, the status of which are not yet clear: relics of Saint Denis and Saint Genevieve, patron saints of Paris, and a supposed tiny piece of the Crown of Thorns acquired by the church in 1239. The relics were originally placed at the summit by the Archbishop Verdier in 1935 to protect the building and its parishioners from harm.

As news of the fire was sweeping the internet, President Trump tweeted: “So horrible to watch the massive fire at Notre Dame Cathedral in Paris. Perhaps flying water tankers could be used to put it out. Must act quickly!” In response, Paris’s civil defense agency dismissed the suggestion on Twitter, noting that the weight and intensity of dropping water by air would do more harm than good, potentially leading the entire structure to collapse and damaging nearby buildings.

So horrible to watch the massive fire at Notre Dame Cathedral in Paris. Perhaps flying water tankers could be used to put it out. Must act quickly!

— Donald J. Trump (@realDonaldTrump) April 15, 2019

Other officials around the world began sending condolences swiftly. Bill de Blasio, the mayor of New York City, said in a statement that “New York City is mourning with Paris.” The Vatican released a statement mourning the damage to the cathedral, which it described as a “symbol of Christianity in France and in the world.” The Metropolitan Museum of Art, meanwhile, tweeted that the museum “and the collective cultural community are watching in shock and horror” and “stand ready to provide any and all resources we can.”

The church—which took more than a century to build and where Napoleon was crowned emperor—has suffered damage before, although likely not of this scale. In the mid-16th century, Huguenots destroyed sculptures in the building that they deemed idolatrous. During the French Revolution in the 1790s, many of its treasures, including the large statues on its facade, were damaged or stolen. During the Second World War, stray bullets punctured some of the medieval glass during the liberation of Paris.

Under French law, the government owns the cathedral; it is operated by the Catholic archdiocese of Paris.

You can see footage of the fire below.

This story will be updated.