People pray as Notre Dame Cathedral burns in Paris on Monday.[CHRISTOPHE ENA/AP]

President Xi Jinping sent his condolences to French President Emmanuel Macron on Tuesday after a fire ravaged the Notre Dame Cathedral in Paris, with the Chinese leader expressing sincere sadness to all French people.

Noting that Notre Dame Cathedral is an iconic symbol of French culture as well as an outstanding treasure of human civilization, Xi said Chinese people feel deeply saddened by the fire, just as the French people do.

Xi said he believes that with the efforts of the French people and support from the international community, Notre Dame Cathedral will be repaired well and regain its glory.

The fire broke out about 6:30 pm on Monday around the roof of the cathedral, which was surrounded by scaffolding. It spread quickly and destroyed the wooden interior before toppling the spire.

It took more than 400 firefighters hours to extinguish the fire, with the main structure and two towers standing. The cause of the fire has not been determined, but is believed to be linked to renovation work. Investigators are preparing to question the team of workers as they look into the cause of the fire.

China can be a helpful partner in rebuilding the 850-year-old Gothic structure, said a historian from Cambridge University.

Alan Macfarlane, historian and professor emeritus at King's College, Cambridge, said that given China's widely acknowledged engineering and construction expertise in the world, "it would be a very appreciated gesture if the people of China offered their help in whatever way the French thought appropriate to rebuild".

"The Chinese have built the largest airport in the world — a far larger job than rebuilding Notre Dame — in less than three years," Macfarlane said. "They could be of immense help."

At the scene of the fire in Paris, Macron vowed an immediate fund­raising drive to rebuild the landmark, calling for international talent to contribute to the effort.

"We will rebuild this cathedral all together and it is undoubtedly part of the French destiny and the project we will have for the coming years. … A national subscription will be launched, and well beyond our borders we will appeal to the greatest talent, and there are many who will come to contribute and rebuild us. We will rebuild Notre Dame, because that's what French people expect, because it's what our history deserves and because it's our deep destiny," said Macron.

Already, two of France's wealthiest men pledged massive donations. Billionaire Francois-Henri Pinault, chairman and CEO of the Kering Group, which owns the Gucci and Yves Saint Laurent fashion brands, pledged 100 million euros ($113 million) to help rebuild Notre Dame, AFP reported.

Shortly after, Bernard Arnault, chief executive of LVMH Group — owner of fashion labels including Louis Vuitton and Bulgari — said he would donate 200 million euros.

Notre Dame, which was built in the 12th and 13th centuries, receives around 13 million visitors each year — even more than the Eiffel Tower. The cathedral is regarded as one of the finest examples of French Gothic architecture and sits at the heart of the nation's history.

"If you think of France as a body, then Notre Dame is in many ways its heart … Its partial loss is a terrible blow to a proud country and to the world more widely," Macfarlane said.

The Cambridge professor said rebuilding efforts will pose a huge challenge, but he remains optimistic as the main structure has survived.

"It is an immense building and the result of centuries of fine craftsmanship," he said.

"But as the structure, made of stone, has survived, so it is as if a body had been badly damaged, but the legs, trunk, arms and even head are still there. Modern techniques of restoration are amazing and it is probable that what has to be replaced is well documented. With patience, money and care it can be done, and though it will not be the same, it will be Notre Dame."

A woman named Marie, who has lived in Paris for 20 years and works at an art gallery, said,"Paris without Notre Dame is not Paris."