French President Emmanuel Macron was preparing to rally his Cabinet behind plans to rebuild the torched Notre Dame Cathedral within five years, a break-neck pace for a project of monumental scale.
France's Prime Minister, Édouard Philippe, announced the creation of an international architecture competition to replace the renowned 19th-century spire that collapsed in the blaze.
"This is obviously a huge challenge, a historic responsibility," Philippe said, noting that the new design would have to be "adapted to technologies and challenges of our times."
Macron's timeline for reconstruction, initially laid out in a speech to the nation yesterday, represents an ambitious approach to a delicate project that will require hundreds, if not thousands, of craftsmen, carpenters, masons and others to restore one of the world's great treasures to its pre-blaze glory.
Today, Notre Dame's rector announced that the cathedral would probably be closed for five to six years.
Some experts have estimated that the reconstruction work could take a decade or more.
But Macron told his fellow citizens that it should be done by 2024, when Paris is due to host the Summer Olympics, and that the restored cathedral will be "even more beautiful."
The President's declaration came as investigators interviewed dozens of workers who had been involved in a long-overdue restoration project at the famed cathedral. Although none of the workers are believed to have been present when the fire broke out, police hope they can offer clues to what sparked the blaze.
Prosecutors have said that they believe the fire was accidental and that there has been no indication it was set intentionally.
But the exact cause remains a mystery. The Parisien newspaper reported that investigators believe an electrical fault in a lift installed temporarily for the restoration work may have been to blame, while acknowledging that remains only a theory.
The newspaper quoted a person close to the investigation as saying it would be "long and difficult" and that "it is possible that we never know what is behind this fire."
Officials have warned that Notre Dame may still have gravely dangerous vulnerabilities, especially in the soaring vault. Paris firefighters said that the cathedral's stained glass rose windows are intact, but their support structures are at risk, according to PA. Camera footage from inside the church showed charred rubble in front of the altar.
Questions remain about whether any warning signs of a fire might have been missed, especially when an alarm first went off and was investigated by the cathedral's on-site "fire watchers." It was only when a second alarm went off - 23 minutes later - that the fire was detected.
By then, the flames were spreading fast, eating up one wooden beam, then another, in a portion of the roof called "the forest" because each massive support was shaped from an entire tree. The 750-tonne spire, which was originally constructed in the 13th century and rebuilt in the 19th out of oak covered with lead, was toppled.
The Parisien reported that a glitch in the computerised fire control system sent church staffers to the wrong part of the cathedral to investigate after the first alarm.
Buildings such as Notre Dame - full of hidden nooks and passages, and composed of ancient timber and other old materials - are seen by fire prevention experts as particularly risky, especially when they are under renovation. Stewart Kidd, a consultant on heritage buildings in Britain, said that in old structures, by the time flames become visible, "they may have been burning for an hour" in unseen spaces.
And when there is construction, Kidd said, "the building is exposed to all sorts of dangerous activity."
Culture Minister Franck Riester said on French radio that much of the cathedral's art and artifacts had been saved. The 8000-pipe grand organ survived the flames - though whether it had suffered water damage was still to be determined. Riester also confirmed that firefighters had rescued the church's two most hallowed relics: the crown of thorns said to have been worn by Jesus and a tunic of Saint Louis, a 13th-century French king.
The objects would be transferred from Paris City Hall to the Louvre Museum, Riester said.
"It was necessary to bring them out through the smoke," Paris Fire Commander Jean-Claude Gallet told BFMTV. He said firefighters rushed into the chamber of the cathedral at the height of the fire to make the rescue.
Vittorio Sgarbi, a Rome-based art historian, said that Notre Dame, even before the fire, had been an architectural mishmash - some parts original, but many parts added or replaced.
"This is going to be a fateful event in the story of a non-authentic building, a sort of laboratory," Sgarbi said.
Philanthropists needed little prompting to contribute to the rebuilding effort. French luxury magnate François-Henri Pinault declared that his family would dedicate about US$113 million to the effort. The family of Bernard Arnault, chief executive of the LVMH conglomerate and the richest man in Europe, pledged US$226 million. The Bettencourt Meyers family behind L'Oreal matched that offer. Companies including Apple and the French oil giant Total also made pledges.
"I am not religious myself; I'm an atheist," said Charles Gosse, 23, a business school student who launched an online funding campaign and quickly raised US$27,000. "But this is beyond religion. It is a national monument like the Eiffel Tower and the Arc de Triomphe."