Parisians gathered in front of Notre Dame on Tuesday night, at a vigil where music was played and attendees prayed for the future of the cathedral.
Investigators are working to establish what led the centuries-old architectural masterpiece to be consumed by flames on Monday evening.
Fifty investigators are working on the probe and will interview workers from five companies, hired to renovate Notre Dame’s roof.
Remy Heitz, the Paris prosecutor, said the inquiry into the Notre Dame fire would be “long and complex”.
Emmanuel Macron, the French president, committed to rebuild the church within five years, in a short public address on Tuesday.
He called for unity and said Notre Dame would be restored to be “even more beautiful”.
“We can do it and once again, we will mobilise,” he said.
Wealthy French benefactors have pledged hundreds of millions of euros to rebuild the famous building after its roof and spire were ravaged by the blaze.
On Tuesday night, monuments around the world were lit up in the colours of the French flag, in a show of solidarity with Paris.
One World Trade Centre, the dome of the Chapel of the Holy Shroud inside the Duomo in Turin and the La Fenice theatre in Venice, were among the monuments taking part in the global gesture.
If you would like to see how the Notre Dame fire unfolded, please see what was our live coverage below:
The Independent will be providing live coverage of the aftermath of the blaze that partially destroyed Paris' Notre Dame cathedral on Monday night.
Inside the 850-year-old building, whose wooden spire was destroyed in the fire, a golden cross appears to have survived.
Officials say the main structure of the cathedral is intact after firefighters managed to prevent the flames spreading to its northern belfry.
French tycoon Bernard Arnault and his luxury goods group LVMH have pledged €200m (£173m) to help rebuilt Notre Dame.
LVMH called the cathedral a "symbol of France, its heritage and its unity".
It comes after another billionaire, Francois Pinault, was reported to have pledged €100m.
Emmanuel Macron has said he will look "beyond our borders" for help rebuilding Notre Dame.
In an emotional address last night he said: "I am solemnly telling you tonight: this cathedral will be rebuilt by all of us together."
Japan has already said it will consider sending help.
For more, read on here.
Pope Francis has said he is "praying for French Catholics and for the people of Paris in face of the terrible fire which has ravaged Notre Dame cathedral", the Agence France-Presse news agency reported.
A French cultural heritage expert has said he believes France no longer has trees big enough to replace the ancient wooden beams destroyed by fire last night.
Bertrand de Feydeau, the vice president of preservation group Fondation du Patrimoine, told France Info radio that the roof had been constructed with more than 800 years ago with beams taken from primal forests.
Speaking on Tuesday, he said the cathedral's roof cannot be rebuilt exactly as it was before the fire because "we don't, at the moment, have trees on our territory of the size that were cut in the 13th century."
He said the restoration work will have to use new technologies to rebuild the roof.
Additional reporting by AP
The fire is now officially extinguished, officials say.
Countries around the world have expressed solidarity with France in the wake of the fire.
Lebanon's prime minister Saad Hariri expressed sadness over the blaze, which he described as a "heritage and humanitarian disaster".
He added in a tweet late on Monday that Lebanon expressed strong solidarity with the "friendly French people".
A Philippine presidential spokesman, Salvador Panelo, said "Our thoughts and prayers are with the people of France as well as in solidarity with the rest of the world for this heartbreaking incident."
South Korean president Moon Jae-in called for the world to come together to rebuild the Paris landmark. He said: "Our love for humanity will be illustrated in a more mature way in the process of reconstruction."
Additional reporting by AP
A spokesman for Paris firefighters has said that "the entire fire is out" at Notre Dame.
Gabriel Plus said emergency services were currently "surveying the movement of the structures and extinguishing smouldering residues" in the 850-year-old cathedral.
Mr Plus added that now the fire is out, "this phase is for the experts" to plan how to make the building safe and prepare for restoration.
While we await more updates this morning, let's take a quick look back at some of our coverage from last night.
As the flames raged, Donald Trump offered some advice to Paris firefighters battling to save Notre Dame.
"Perhaps flying water tankers could be used to put it out. Must act quickly!" the US president tweeted.
Later, he added: "God bless the people of France!"
He also called the cathedral "one of the great treasures of the world".
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies