French president Emmanuel Macron has promised to rebuild Notre-Dame Cathedral after the fire, and millions of euros have already been pledged in support.
"This Notre-Dame Cathedral, we will rebuild it. All together," Macron wrote on Twitter late last night, after the fire has already destroyed the roof and spire of the historic Paris cathedral.
"This is part of our French destiny," he said. "I am committed to this: from tomorrow a national subscription will be launched, and far beyond our borders."
More than €300 million pledged
French billionaire Bernard Arnault and his company, luxury accessories brand LVMH, have offered €200 million (£173 million), according to French media outlet AFP.
An additional €100 million (£86 million) has been pledged by the Pinault family, which owns fashion conglomerate Kering and investment firm Artemis. Francois-Henri Pinault, who is married to Hollywood actress Salma Hayek, said the plan should be to "completely rebuild Notre-Dame".
Paris mayor Anne Hidalgo has promised to unlock city funding for the cause, as well as to lead a fundraising drive.
"I propose that we organise in the coming weeks a major international conference of donors, which I am ready to welcome to the city hall, with patrons from all over the world, in order to raise the necessary funds for restoration," she wrote on Twitter.
A further €10 million will be put forward by the Ile-de-France regional government said president Valerie Pecresse, according to AFP.
Hope for restoration
The fire broke out around 7pm local time and it took firefighters nine hours to bring it under control. The roof was destroyed, while the 90-metre-high spire collapsed in front of crowds.
However the blaze was stopped short of the two bell towers at the front of the cathedral. The exterior walls were largely also saved, although the building's wooden interior has suffered extensive damage.
Many historic artefacts within the cathedral were saved in the rescue mission, including the woven crown of thorns and the tunic of Saint Louis. They are now being temporarily stored at the city hall.
Experts are hopeful that the building can be accurately repaired, using laser scans made by art historian Andrew Tallon, which map the entire structure of the building.
UNESCO plans "emergency mission"
UNSECO has pledged support in the rehabilitation of the cathedral, which forms part of the Paris, Banks of the Seine world heritage site.
"We are all heartbroken," said UNESCO director-general Audrey Azoulay.
"Notre Dame represents a historically, architecturally, and spiritually, outstanding universal heritage. It is also a monument of literary heritage, a place that is unique in our collective imagination. Heritage of the French but also of humanity as a whole."
She said that damage assessment would be undertaken as soon as possible.
"UNESCO stands by France in safeguarding and rehabilitating this invaluable heritage," she said. "We are already in contact with experts and ready to send an emergency mission to assess the damage, preserve what can be preserved and plan short- and medium-term measures."
Cause of fire still not known
This is also not the first time the building has suffered major damage. In the 16th century many of its statues were destroyed by rioting Huguenots, while during the French Revolution in the 1790s, much of the religious imagery inside the cathedral was desecrated.
The cause of the fire is still unconfirmed but believed to be linked to renovation works.
As one of the world's finest examples of gothic architecture, the building was undergoing major repairs to its stone walls and structure.
As part of the works, 16 copper statues had been temporarily removed from the building's spire, so were not destroyed when it collapsed. However some other statues had recently been reinstalled elsewhere and will have suffered damage.
Main image is from Getty Images.