Parisians gave thanks yesterday to see the bell towers and great stained-glass rose window of Notre-Dame still standing, after firefighters laboured through the night to douse the flames that gutted one of the most potent national symbols of France.
Authorities said they suspected the fire was caused by accident.
President Emmanuel Macron declared that the cathedral would be rebuilt.
Industrialists pledged hundreds of millions of euros.
Ordinary people sang, wept and prayed below the cathedral that has towered above the capital for more than 800 years.
More than 400 firefighters were needed to tame the inferno that consumed the roof and collapsed the spire of the gothic masterpiece.
They worked through the night, finally quelling the blaze some 14 hours after it began.
“Yesterday we thought the whole cathedral would collapse. Yet this morning she is still standing, valiant, despite everything,” said Sister Marie Aimee, a nun who had hurried to a nearby church to pray as the flames spread. “It is a sign of hope.”
From the outside, the imposing bell towers and outer walls, with their vast buttresses, stood firm, though the insides and the upper structure had been eviscerated.
Paris public prosecutor Remy Heitz said there was no obvious indication the fire was arson.
Fifty people were working on what would be a long and complex investigation, officials said.
One firefighter was injured but no one else was hurt, with the fire starting around 6.30pm after the building was closed to the public for the evening.
Firefighters examined the facade, with its spectacular 10m filigreed stained-glass rose window still intact.
They could be seen walking atop the belfries as police kept the area in lockdown.
Investigators will not be able to enter the cathedral’s blackened nave until experts are satisfied that its walls withstood the heat and the building is structurally sound.
The fire swiftly ripped through the cathedral’s oak roof supports, where workmen had been carrying out extensive renovations to the spire’s timber-framed supports.
The Paris prosecutor has opened an investigation into “involuntary destruction by fire”.
Interior Ministry state secretary Laurent Nunez said that specialists had found “some weaknesses” in the cathedral following the fire, especially in the dome.
However, he added, overall the structure was holding quite well.
Though the reason for the fire has yet to be determined, Patrick Chauvet – the rector of the cathedral – told broadcaster France Inter that that there had been wardens checking the roof for fire hazards three times a day.
“I think there is nothing more you can do,” Chauvet said, adding that the public would now have to wait for the outcome of official investigations.
Yesterday police began questioning the workers involved in the restoration, the prosecutor’s office said.
Hundreds of stunned onlookers had lined the banks of the river Seine late into the night, reciting prayers and singing as they stood in vigil while the fire raged.
It was at Notre-Dame that Henry VI of England was crowned “King of France” in 1431, that Napoleon was made emperor in 1804, and Pope Pius X beatified Joan of Arc in 1909.
Presidents Charles de Gaulle and Francois Mitterrand were mourned there.
Messages of condolence flooded in from around the world.
Pope Francis, the leader of the Catholic Church, was praying for those affected, the Vatican said, adding: “Notre-Dame will always remain – and we have seen this in these hours – a place where believers and non-believers can come together in the most dramatic moments of French history.”
Britain’s Queen Elizabeth II expressed deep sadness while her son and heir Prince Charles said he was “utterly heartbroken”.
Chancellor Angela Merkel offered German help to rebuild a part of “our common European heritage”.
European Council President Donald Tusk called on all 28 EU member states to help rebuild the Notre Dame Cathedral, while recalling his home city of Gdansk in Poland, which was rebuilt after World War II following widespread destruction.
“You will also rebuild your cathedral,” Tusk said during a European Parliament session in the French city of Strasbourg. “I call on all the 28 member states to take part in this task.”
“I know that France could do it alone, but at stake here is something more than just material help,” Tusk said, adding: “We are bound by something more important and more profound than treaties.”
German Foreign Minister Heiko Maas said that Berlin stood ready to give its support as a close friend of Paris.
Considered among the finest examples of European Gothic architecture, Notre-Dame is visited by more than 13mn people a year.
It sits on an island in the Seine, overlooking the Left Bank hangouts of Ernest Hemingway and Pablo Picasso.
“Notre-Dame de Paris is the cathedral of the people, of the people of Paris, of the French people, of the people of the world. It is part of those references of our history, of what we have in common, of what we share,” said Interior Minister Christophe Castaner.
The company carrying out the renovation works when the blaze broke out said it would co-operate fully with the investigation.
“All I can tell you is that at the moment the fire began none of my employees were on the site. We respected all procedures,” Julien Le Bras, a representative of family firm Le Bras Freres.
The steeple of the Gothic edifice had been undergoing an €11mn ($12.4mn) overhaul financed by the French state to repair damage inflicted by time, pollution and the weather.
The cathedral has long relied on individual donations for repairs, and a few years ago created a US-registered charity enabling American voters to deduct gifts from their taxes.
Officials breathed a sigh of relief that many relics and artworks had been saved.
At one point, firefighters, police officers and municipal workers formed a human chain to remove the treasures, including a centuries-old crown of thorns made from reeds and gold, and the tunic believed to have been worn by Saint Louis, a 13th century king of France.
“Notre-Dame was our sister, it is so sad, we are all mourning,” said Parisian Olivier Lebib. “I have lived with her for 40 years. Thank God that the stone structure has withstood the fire.”
The cathedral is owned by the state and has been at the centre of a years-long row between the nation and the Paris archdiocese over who should finance restoration work to collapsed balustrades, crumbling gargoyles and cracked facades.
Prime Minister Edouard Philippe held a ministerial round for consultations on reconstruction, with Culture Minister Franck Riester and the minister for public accounts, Gerald Darmanin, in attendance.
Within 24 hours, companies and local authorities had pledged more than €700mn to rebuild it, including €500mn from the three billionaire families that own France’s giant luxury goods empires: Kering, LVMH, and L’Oreal.
Kering, whose brands include Yves Saint Laurent and Gucci, kicked off the campaign late on Monday with a promise of €100mn ($113mn).
It was followed yesterday by a €200mn pledge from Kering’s rival LVMH and the family of its founder Bernard Arnault, France’s richest person.
The L’Oreal cosmetics group and its founding Bettencourt family offered €200mn, while French oil giant Total said it would contribute €100mn.
Several other business executives and blue-chip French firms also said they would contribute, some announcing pledges of €5mn, €10mn or €20mn.
It was too early to estimate the cost of the damage, said the heritage charity Fondation du Patrimoine.
Air France said it would offer free flights to experts brought in to help with Notre-Dame’s renovation, while glass giant Saint-Gobain promised its expertise in restoring the stained-glass windows which exploded in the fire.
Support came from outside France as well, with Apple chief Tim Cook announcing the tech giant would give an unspecified amount to help restore a “precious heritage for future generations”.
Some gripes emerged on social media over the huge fiscal deductions companies in both France and the US would be eligible for, with commentators saying that taxpayers would be footing much of the final bill.
But pledges were also pouring in from anonymous donors to groups, including the privately-run French Heritage Foundation, which said it had secured more than €13mn in pledges.
On a more modest scale, a fund set up on the Leetchi fundraising platform had reached nearly €29,000 by afternoon yesterday.
France 2 television said it will broadcast a special classical music concert tonight as part of the fundraising effort.
The French Council of the Muslim Faith also called on French Muslims to help save “an architectural masterpiece that is the honour of our country”.
Paris Mayor Anne Hidalgo said the city would unlock €50mn, while the government of the greater Paris region promised €10mn.
And French insurer Groupama said it would supply the estimated 1,300 huge oak beams needed to re-create the intricate roof support.
The German and Italian governments have also offered to help in the reconstruction, while Russian President Vladimir Putin offered to send “the best Russian specialists with rich experience in the restoration of national heritage monuments”.
Paolo Violini, a restoration specialist for Vatican museums, said that the pace at which the fire spread through the cathedral had been stunning.
“We are used to thinking about them as eternal simply because they have been there for centuries, or a thousand years, but the reality is they are very fragile,” Violini said.