About 400 firefighters battled the fire that destroyed timber roof of the 850-year-old building in Paris.

Paris firefighters have declared Notre Dame Cathedral saved late on Monday even as flames continued to burn in the wreckage of the Western cultural icon’s roof.

The huge blaze, that started a little over four hours earlier, destroyed the timber roof of the Gothic building and about two hours into the conflagration, the upper part of the 93-metre-high spire swayed and fell as flames shot up.

About 400 firefighters battled the fire, aiming jets of water at the 850-year-old cathedral as solemn crowds watched quietly from behind police cordons.

Fire chief Jean-Claude Gallet said that the structure of the cathedral had been “saved and preserved overall” and its bell towers, at one point thought to be at risk, were safe.

French media reported that the fire might have been linked to renovation work. The Paris prosecutor’s office said that “as matters stand” it was investigating a count of “involuntary destruction by fire”.

The cathedral’s most precious relics had been saved, rector Monsignor Patrick Chauvet said.

Shortly afterwards, French President Emmanuel Macron said “the worst has been avoided, even if the battle has not been fully won”. Calling the cathedral “the very centre of our lives”, he vowed that France “will rebuild Notre Dame”.

“It is what French people expect, because it is what our history deserves, because it is our deep destiny,” he told reporters at the scene.

His statement came as Parisians and visitors gathered to watch in horror and disbelief from the nearby banks of the River Seine as emergency workers fought back enormous flames coming out of the iconic Gothic landmark. The firefighters were unable to save the building’s spire, which was toppled by the blaze, and large swaths of the structure’s roof.

Smoke billows as fire engulfed the spire of Notre Dame cathedral [Benoit Tessier/Reuters]

The cathedral was in the middle of a $6.8m renovation, with some sections under scaffolding, while bronze statues were removed last week for works.

A church spokesman said the entire wooden interior of the 12th-century landmark was burning and likely to be destroyed.

Those living close to the cathedral have been evacuated in case of a possible collapse of the building, Paris Mayor Anne Hidalgo said.

France‘s civil security agency said “all means” except for water-dropping aircraft were deployed to put out the flames.

But the defence agency said those were unsuitable for fires like the one at Notre Dame because dumping water on the building could cause the whole structure to collapse.

https://twitter.com/patrickgaley/status/1117848909877895171?ref_src=twsrc^tfw

“A terrible fire is under way at Notre Dame Cathedral in Paris,” Mayor Anne Hidalgo said earlier on Twitter. “There are a lot of artworks inside … it’s a real tragedy,” she later told reporters at the scene.

Police urged people to avoid the area and facilitate the passage of emergency vehicles.

Al Jazeera’s Natacha Butler, reporting from Paris, said she saw tears streaming down the face of some onlookers.

“The cathedral is a French icon, it is a symbol of Paris all over the world,” she said. “To see it in flames is extremely sad for so many people.”

The iconic structure in central Paris in flames [Benoit Tessier/Reuters]

Claire, a 15-year-old onlooker, told Al Jazeera crying: “Notre Dame is the heart of Paris and I came as soon as I heard. This is our heart and it is disappearing in the flames. What do we have left?”

Yvette, a French-American student, told Al Jazeera: “I came as soon as I could because I didn’t know how bad the fire was going to be or how much of the structure was still going to be standing, and I wanted to stand witness while it was still here.”

Nedjma, another witness in Paris, said she saw the fire on her way home from work.

“As we walked, we could feel ashes on our faces. Everyone was really shocked by this,” she told Al Jazeera. “It’s a huge monument and a huge part of Paris’s history.”

Notre Dame, Paris, is on fire and it feels like the end of the world. pic.twitter.com/qYYk7ewipq — Shiv Malik (@shivmalik) April 15, 2019

Notre Dame is celebrated for its size, antiquity and architectural interest.

The cathedral, which is famous for featuring in Victor Hugo’s classic novel The Hunchback of Notre Dame, attracts millions of tourists every year.

It was here that Christian crusaders prayed before going to fight in the Holy Land, where revolutionaries defiled representations of French kings and Napoleon crowned himself emperor in 1804.

“It’s a devastating image because Notre Dame, Paris and France play a key role in the history of European Christendom, that is second only to Rome and the Vatican,” Massimo Faggioli, a professor of theology and religious studies at Villanova University, told Al Jazeera.

“This is really a fire at the heart of Christianity,” he added.

French historian Camille Pascal, meanwhile, told France’s BFM television news channel the blaze marked “the destruction of invaluable heritage”.

“It has been 800 years that the Cathedral watches over Paris … happy and unfortunate events for centuries have been marked by the bells of Notre Dame,” Pascal said.

“We can be only horrified by what we see.”

Victoria Baux contributed to the report