President Donald Trump tweeted about the massive fire engulfing Notre Dame Monday, suggesting the use of flying water tankers to douse the flames – then appeared to criticize renovation work that may have caused it.

Trump tweeted from aboard Air Force One en route to Minnesota, while viewers around the world were watching the iconic cathedral in flames.

'So horrible to watch the massive fire at Notre Dame Cathedral in Paris. Perhaps flying water tankers could be used to put it out. Must act quickly!' Trump wrote while en route to Minnesota for an event about taxes.

Later, at his Tax Day event, Trump told a crowd about the 'terrible, terrible fire.'

'The fire that they're having at the Notre Dame Cathedral is something like few people have witnessed,' the president said.

'When we left the plane, it was burning at a level that you rarely see a fire burn. It's one of the great treasures of the world,' Trump continued.

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President Donald Trump tweeted about the fire at Notre Dame Monday

'It’s one of the great treasures in the world. The greatest artists in the world. Probably if you think about it … it might be greater almost than any museum in the world and it’s burning very badly. Looks like It’s burning to the ground,' the president added, as firefighters struggled to contain the blaze.

Trump said he had a 'communication' with France but did not specify if he spoke to French authorities.

'That puts a damper on what we’re about to say to be honest,' Trump told his audience in Minnesota. 'Because that is beyond countries. That’s beyond anything. That’s a part of our growing up, it’s a part of our culture, it’s a part of our lives. That’s a truly great cathedral. And I’ve been there and I’ve seen it … There’s probably no cathedral in the world like it,' Trump said.

The president said the French believe the fire was related to the ongoing renovation of the 850-year-old cathedral.

'They think it was caused by renovation. And I hope that's the reason,' Trump continued. 'Renovation. What's that all about?' Trump said. Then he called it a 'terrible sight to behold.'

'With that being said, I want to tell you that a lot of progress has been made by our country in the last two and a half years, ' Trump said, segueing into his tax event. 'Hard to believe we're already starting to think about our next election.'

The president suggested the use of airborne tankers

The French government tweeted out its reason in English for not using water tankers from the air

At the end of his roundtable event, where he hailed tax cuts, gains against ISIS and other matters, Trump returned to Notre Dame.

'We all want to extend our regards and our hopes and our "God Bless you" to Paris and to France, what they're going through,' Trump said.

'This is one of the true catastrophes,' he said. 'Hopefully they did better than they were doing when I left the plane but it was not a good situation with respect to Notre Dame Cathedral.'

CNN reported hours after Trump's tweet that the French government responded to questions about the lack of air tankers. The reason was not due to a lack of capability, but rather to concerns that air drops could cause the cathedral's walls to implode, according to the report.

France's ambassador to the U.S., Gerard Araud, told the network: 'It's not possible to use water tankers which could only worsen he situation of the building.' He mentioned the difficulty of containing the fire with intense heat and tons of wood acting as fuel. 'So I think we have only to pray now,' he said.

The French civil security division posted a tweet that appeared to rebut Trump – posting single English language missive on its French-language account.

'Hundreds of firemen of the Paris Fire Brigade are doing everything they can to bring the terrible #NotreDame fire under control. All means are being used, except for water-bombing aircrafts which, if used, could lead to the collapse of the entire structure of the cathedral,' according to the tweet.

First lady Melania Trump, who did work in Paris during her modeling career, also tweeted about the fire.

'My heart breaks for the people of Paris after seeing the fire at Notre Dame Cathedral. Praying for everyone’s safety,' Melania Trump wrote.

PARIS, FRANCE - APRIL 15: Flames and smoke rising from the Notre Dame cathedral in Paris, France on April 15, 2019

A fire broke out at the landmark Notre-Dame Cathedral in central Paris, potentially involving renovation works being carried out at the site, the fire service said.Images posted on social media showed flames and huge clouds of smoke billowing above the roof of the gothic cathedral, the most visited historic monument in Europe

The president suggested: 'Perhaps flying water tankers could be used to put it out.' Above an air tanker drops water on a fire along the Ronald Reagan (118) Freeway in Simi Valley, Calif., Monday, Nov. 12, 2018

The president had the capability to monitor televised reports while in flight to Minnesota.

Televised coverage showed billowing smoke and flames engulfing the roof of the building, but scant few early signs of an effective firefighting response.

One helicopter was seen circling the area as Parisian firefighters made their way to the seen.

There were no early images of any immediate effort from the air. Firefighters eventually were able to assemble fire boats on the river. The cathedral is located on the corner of Ile de la Cite, on a spit of land that juts out into the river Seine.

It wasn't immediately known why there weren't air capabilities deployed, or whether they even were available.

'My heart breaks for the people of Paris after seeing the fire at Notre Dame Cathedral. Praying for everyone’s safety,' Melania Trump wrote Monday

Ivanka Trump tweeted about the event from Ethiopia

The president's daughter, traveling in Africa, also tweeted about the event.

'Watching flames engulf the iconic Notre Dame Cathedral in Paris. A devastating and shocking sight. Praying for the safety of all,' Ivanka Trump wrote.

According to French newspaper Le Monde, the fire broke out in the attic of the monument before spreading across the roof.

The cathedral is one the finest example of French Gothic architecture in Europe, and one of the most visited buildings in the world.

Notre Dame - which means 'Our Lady' - was build in 1160 and completed by 1260, and has been modified on a number of occasions throughout the century.

Vice President Mike Pence tweeted Monday: 'Notre Dame is an iconic symbol of faith to people all over the world – and it is heartbreaking to see a house of God in flames. Our thoughts and prayers are with the firefighters on the scene and all the people of Paris.'