Prince Albert, Grace Kelly's son, sends letter of solidarity to Emmanuel Macron following Notre Dame fire

French President Emmanuel Macron and Prince Albert II of Monaco on Dec. 12, 2017 in Paris. (Photo by Aurelien Meunier/Getty Images)

Prince Albert II of Monaco, the son of late American actress-turned-royal Grace Kelly, is “deeply saddened” by the horrific fire that ravaged the Notre Dame Cathedral in Paris, Fox News has learned Thursday.

“[I am] deeply saddened by the terrible fire that devastated the Notre Dame Cathedral in Paris, the emblematic heart of the capital. On behalf of the people of Monaco, my family and myself, we want to express our support and our solidarity,” wrote the 61-year-old reigning monarch in a letter sent to French President Emmanuel Macron.

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“My thoughts also go to the fire department for its determined and courageous battle against this fire that destroyed a medieval Gothic treasure whose architecture, paintings and sculptures bear witness to 850 years of history,” continued Albert.

Firefighters tackle the blaze as flames and smoke rises from Notre Dame cathedral as it burns in Paris, Monday, April 15, 2019. Massive plumes of yellow-brown smoke are filling the air above Notre Dame Cathedral and ash is falling on tourists and others around the island that marks the center of Paris. (AP Photo/Michel Euler)

“I also send my thoughts to the people of France who are so affected by the disaster that this cathedral has suffered, a place of worship and prayer, but also a cultural landmark and symbol of the history of France.

“Also, our community is moving to make a financial contribution to the renovation work planned to revive the splendor of this world heritage whose spiritual, cultural and artistic influence will continue. Please accept, the assurance of my highest consideration.”

The declaration comes days after a devastating fire raged through the historical cathedral for more than 12 hours, ultimately destroying its spire and roof but sparing its twin medieval bell towers. As the blaze roared, there was a frantic effort to rescue the monument’s “most precious treasures,” including the Crown of Thorns said to have been worn by Jesus.

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A priest wipes the Crown of Thorns, a relic of the passion of Christ- at the Notre-Dame Cathedral in Paris on April 14, 2017. (PHILIPPE LOPEZ/AFP/Getty Images)

Also surviving was the Roman Catholic cathedral’s famous 18th-century organ that boasts more than 8,000 pipes. Statues removed from the roof for restoration just days before were spared. The cathedral’s high altar was damaged by falling debris when the spire collapsed, an official said.

Remarkably, no one was killed in the blaze, which occurred during a Mass, after firefighters and church officials speedily evacuated everyone inside. Since the fire, donations have been pouring in all over the world. It surpassed the $1 billion mark Wednesday.

Although authorities consider the fire an accident, possibly as a result of restoration work at the global architectural treasure that survived almost 900 years of French history, Paris prosecutor Remy Heitz said the inquiry into what caused the fire would be “long and complex.”

Fifty investigators were working on it and are expected to interview workers from five companies hired for the renovations to the cathedral’s roof, where the flames first broke out.

Firefighters are seen with a robot firefighter called Colossus, made by French robotics company Shark Robotics, outside Notre-Dame Cathedral after a major fire yesterday on April 16, 2019, in Paris, France.  (Aurelien Meunier/Getty Images)

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Among those will likely be Julien Le Bras.

The young construction boss bragged about his company's ability to protect historic sites when he landed the lucrative $5.6 million deal to repair the famed cathedral's spire.

Bras, 32, owns the company Le Bras Freres. He has boasted in the past that "our first thought is to protect the values of historical buildings" and that "it's in our DNA."

A hole is seen in the dome inside Notre Dame cathedral in Paris, Tuesday, April 16, 2019.  (Christophe Petit Tesson, Pool via AP)

UK's Daily Mail reported Tuesday that workers from his company are being questioned by investigators.

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As the probe into what happened continues, the Paris Fire Brigade shared dramatic footage of the roof of the cathedral engulfed in flames and billowing clouds of smoke. The incredible video also shows firemen and women racing into the burning building to save it from destruction.

On Tuesday, Macron vowed to rebuild the badly burned Norte Dame Cathedral in five years, as dramatic footage was released showing the heroism of firefighters who battled the blaze for hours.

French President Emmanuel Macron sits at his desk after addressing the French nation following a massive fire at Notre Dame Cathedral, at Elysee Palace in Paris, on April 16, 2019.  (Yoan Valat, Pool via AP)

“We will rebuild Notre Dame even more beautifully and I want it to be completed in five years," Macron said in a televised address to the nation. "We can do it."

“It is up to us to change this disaster into an opportunity to come together, having deeply reflected on what we have been and what we have to be and become better than we are. It is up to us to find the thread of our national project," he said.

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Macron added that Monday's inferno "reminds us that our story never ends. And that we will always have challenges to overcome. What we believe to be indestructible can also be touched."

Princess Grace Kelly with her firstborn, Prince Albert. (Getty)

Prince Albert’s mother was an Oscar-winning movie icon and Alfred Hitchcock's muse when she married his father, Prince Rainier of Monaco, in 1956, after meeting him the year before during the Cannes Film Festival.

Kelly famously left behind Hollywood to embark on her new role as a princess when she married Rainier. Kelly died in 1982 at age 52 from injuries she suffered in a car crash in France.

In 2016, Albert purchased Kelly’s childhood home in Philadelphia and renovated it to look like it did when his mother lived there. Toby Boshak, executive director of the Princess Grace Foundation-USA, told NBC’s “Today” in May that the six-bedroom, 2.5 story colonial home will be used occasionally by Albert and his family.

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Prince Albert continues to honor the legacy of his late mother Grace Kelly. (AP)

It will also house offices for the Prince Albert II of Monaco Foundation and hose events for the Princess Grace Foundation-USA, which provides scholarships to emerging talent in theater, dance and film.

Kelly and Rainier announced their engagement at that house. She is survived by three children: Albert, Caroline, Princess of Hanover and Stephanie.

Fox News’ Barnini Chakraborty, Lucia I. Suarez, Nicole Darrah and The Associated Press contributed to this report.