The raging fire that tore through Notre-Dame Cathedral in central Paris was under control early Tuesday after the blaze brought its towering spire and roof crashing to the ground, wiping out centuries of priceless heritage central to French culture and history.

French President Emmanuel Macron vowed to rebuild the cathedral described as the soul of the nation and expressed relief that "the worst had been avoided" in a blaze that had at one point threatened the entire edifice.

Thousands of Parisians and tourists watched in horror from nearby streets cordoned off by the police as flames engulfed the building and officials tried to save as much as they could of the cathedral's countless treasures, built up over centuries.

The inferno destroyed the roof of the 850-year-old UNESCO world heritage landmark, whose spectacular Gothic spire collapsed as orange flames and clouds of grey smoke billowed into the early evening sky.

Around 400 firefighters battled into the night to control the flames, declaring in the early hours of Tuesday that it was partially extinguished but completely under control, around nine hours after it broke out.

Paris fire brigade chief Jean-Claude Gallet said "we can consider that the main structure of Notre-Dame has been saved and preserved" as well as the two bell towers.

But "the whole of the roof has been devastated... a part of the vault has collapsed, the spire is no more", fire brigade spokesman Lieutenant-Colonel Gabriel Plus said.

Laurent Nunez, state secretary at the interior ministry, told reporters early Tuesday that with the immediate "danger of the fire over," the focus would be on assessing the damage to the building's structure.

Nunez said officials would meet shortly to see if the building was stable enough to allow fire services to go inside.



- 'France is Notre Dame' -

"Notre-Dame survived all the wars, all the bombardments. We never thought it could burn. I feel incredibly sad and empty," Stephane Seigneurie, a consultant who joined other shocked onlookers in a solemn rendition of "Ave Maria" as they watched the fire from a nearby bridge.

Gasps and cries of "Oh my god" erupted around an hour after the fire first broke out when the top portion of the church's spire came crashing down.

"We have been dealt a knockout blow," a stricken-looking Paris Archbishop Michel Aupetit told reporters.

The cause of the blaze was not immediately clear, but the cathedral had been undergoing intense restoration work which the fire service said could be linked to the blaze.

French prosecutors said it was being currently being treated as an accident.

Historians expressed dismay at the collapse of a building that has been a symbol of France for almost a millennium.

"If Paris is the Eiffel Tower then France is Notre Dame. It's the entire culture, entire history of France incarnated in this monument," Bernard Lecomte, a writer and specialist in religious history told BFM TV.

Deputy Paris mayor Emmanuel Gregoire told the channel that workers were scrambling "to save all the artworks that can be saved."

Officials later said teams had managed to salvage an unknown quantity of the cultural treasures.


- 'Emotion of a nation' -

Macron cancelled a planned national policy speech on recent "Yellow Vest" protests and instead headed to the scene, where he vowed the cathedral would be reborn.

"We will rebuild Notre-Dame because it is what the French expect," he said, describing Notre Dame as "the epicentre of our life" and the cathedral of "all the French", whether religious or not.

France's billionaire Pinault dynasty immediately pledged 100 million euros for the reconstruction effort.

German Chancellor Angela Merkel called Notre-Dame cathedral a "symbol of European culture" as the blaze raged.

The Vatican on Monday expressed its "incredulity" and "sadness" over the fire.


- 'Water bombers not used' -

One firefighter was injured in the blaze, the fire brigade said, revising an earlier assessment that the individual was in a serious condition.

US President Donald Trump in a tweet said it was "horrible" to watch the fire but caused controversy by offering advice on how to put it out.

"Perhaps flying water tankers could be used to put it out. Must act quickly!" he said.

But France's civil security service, which oversees crisis management in the country, tweeted back at Trump that the use of water-bombing aircraft was not being considered.

"If used, (this) could lead to the collapse of the entire structure of the cathedral," it said.

- 'Will never be the same' -

The cathedral is located at the very centre of the French capital and its construction was completed in the mid-12th century after some 200 years of work.

During the French Revolution in the 18th century, the cathedral was vandalised in widespread anti-clerical violence: its spire was dismantled, its treasures plundered and its large statues at the grand entrance doors destroyed.

It would go on to feature as a central character in a Victor Hugo novel published in 1831, "The Hunchback of Notre-Dame" and shortly afterwards a restoration project lasting two decades got under way, led by architect Eugene Viollet-le-Duc.

The building survived the devastation of two global conflicts in the 20th century and famously rang its bells on August 24, 1944, the day of the Liberation of Paris from German occupation at the end of the World War II.

"Paris is disfigured. The city will never be like it was before," said Philippe, a communications worker in his mid-30s.

Jacky Lafortune, a 72-year-old artist and self-described atheist stood forlornly on the banks of the River Seine staring at the burning cathedral.

Comparing the mood in the French capital to the aftermath of a terror attack he said: "But this stirs much deeper emotions because Notre-Dame is linked to the very foundations of our culture." (AFP)