French firefighters used high-tech kit including drones and a remote controlled robot called Colossus to tackle the devastating blaze at Notre Dame cathedral.
The 500 kg robot was sent into the inferno to tackle the flames on the huge timber roof of the cathedral which posed a major risk to firefighters.
The robot, made by a firm called Shark Robotics, is built to endure tough conditions.
It can be operated from almost 1,000 feet away and was used during the fire to carry heavy hoses into the cathedral and spray a column of water skywards while keeping firefighters at a safe distance.
The robot, almost 5.25 feet long and 2.5 feet wide, is controlled by a trained operator who uses a device that looks like video game controller.
Firefighters also used drones to tackle the blaze, flying them high above the cathedral to identify hotspots to direct their response.
Gabriel Plus, a spokesman for the French firefighters, said: “It is thanks to these drones, to this new technique, that we could make tactical choices to stop this fire at a time when it was potentially occupying the two belfries.”
“The drones allowed us to use our available means in the best possible way.”
Video released by the French Ministry of the Interior shows some of the drone footage as well as their operators.
The fund for the restoration of the cathedral was today approaching one billion euros, as donations flooded in from around the world.
Bernard Arnault, Europe’s richest man, donated 200m euros, Salma Hayek’s husband Francois Henri Pinault donated 100m euros. Cosmetics giant L’Oreal gave 200m euros and oil firm Total gave another 100m euros. The Socialist Council in Paris also pledged 50m euros.
Today, an expert said he believed a modern restoration of Notre Dame would be the best use of the hundreds of millions of euros pledged – rather than being “stuck with the past.”
Professor Stephen Murray, who co-led a project to laser map the Gothic masterpiece in minute detail, said the building was “revolutionary” for its day and the vast sums of money could be used for a cutting-edge update.
Notre Dame was within “15 to 30” minutes of complete destruction during the disastrous blaze that claimed the roof and spire, junior interior minister Laurent Nunez said.
Huge sums have been pledged to repair the beloved Paris landmark, which President Emmanuel Macron has set a target of five years to finish.
He said France “will rebuild Notre Dame Cathedral even more beautifully” as he addressed the nation little more than 24 hours after the devastating fire.
Asked if there should be a modern answer for the building’s restoration, Prof Murray said: “That’s what Gothic was all about”.
“The 12th-century cathedral of Notre Dame of Paris was the highest-tech vision of a building they could conceive,” he told the BBC’s World Tonight.
“It was really a revolutionary building and the roof was a revolutionary piece of carpentry and I don’t think we should be stuck with the past.
“We are children of the 21st century”.
Prof Murray, who studied at Oxford University and the University of London’s Courtauld Institute, co-led a project that used laser scanners and ultra-high-definition photography to document the building.
The expert on medieval art and Gothic architecture is now at Columbia University in New York.
He said the building’s exterior would stay “very much the same” and the interior vaults would be restored, but suggested the roof could be radically different.
Prof Murray said he expects the project to rebuild Notre Dame, which has received international offers of support, will unify France.
“Gothic architecture was very much about unifying a society in the great struggle to create something almost miraculous, and I suspect that’s something we are going to see now in the 21st century,” he said.
“Gothic architecture has been a way of bridging gaps and social divisions and silly arguments to pull people together to build something marvellous.”
Mr Macron announced a national subscription to help rebuild the monument as more than 600 million euros (£519 million) were pledged by firms and wealthy individuals.
Donors to the restoration project include French tycoon Bernard Arnault and his luxury goods group LVMH, pledging 200 million euro (£173 million) after a reported 100 million euro (£86 million) donation was promised by another French billionaire, Francois Pinault.
L’Oreal Group, the Bettencourt Meyers family and the Bettencourt Schueller Foundation jointly also pledged 200 million euro, while oil and gas company Total said it would give 100 million euro towards reconstructing the “architectural jewel”.
Fifty investigators are now working on a “long” and “complex” probe into the cause, Paris prosecutor Remy Heitz told reporters.
They will interview workers from five companies hired to work on renovations to the cathedral roof.
It is believed the blaze was an accident, possibly as a result of restoration work taking place.
At one point it was feared the cathedral would be completely destroyed in the blaze, which lasted more than 12 hours.
The tragedy prompted an outpouring of support internationally, with the Queen saying she was “deeply saddened” and Pope Francis offering his prayers.
The bells at Westminster Abbey tolled at 5.43pm on Tuesday afternoon – 24 hours after the fire started – and Prime Minister Theresa May announced bells at churches and cathedrals across England would ring in a further show of solidarity on Maundy Thursday.
She described images of the destruction as “truly heart-rending”, adding: “President Macron has pledged to rebuild the cathedral and I have conveyed to him that the UK will support this endeavour however we can.”
The cathedral housed a collection of valuable treasures, some which were salvaged and are due to be moved to the Louvre museum.
Speaking in front of the cathedral, junior interior minister Laurent Nunez said: “The task is – now the risk of fire has been put aside – about the building and how the structure will resist.”
Many Parisians spent Tuesday mourning viewing the destruction of one of the city’s most popular and admired landmarks.