Two French billionaires have already pledged a total of 300 million euros toward the cathedral's reconstruction.
Most of the roof has been destroyed, its steeple has collapsed and an unknown number of artifacts and paintings have been lost.
The cathedral's famous 18th-century organ which boasts more than 8000 pipes also survived.
Firefighters removed statues inside the gables, or support walls, above the rose windows to protect them, and took care not to spray water too hard on the delicate stained glass, Mr Plus said.
The fire at the 856-year-old cathedral began Monday evening local time.
"Emotionally, everyone is devastated and struck, but let's be clear, the main stone structure of the cathedral is standing", Jean-Louis Cohen, a professor of the history of architecture at New York University Institute of Fine Arts, told Al Jazeera. "And we can do it".
The Paris prosecutor's office has said it is treating the fire as an accident, since there is no evidence of arson or terrorist activities.
Countries including the United Kingdom and Russian Federation have also offered their best experts to help with the rebuilding efforts, as individual donations towards the rebuilding continue to rise.
"If you've been to the cathedral, you'll never forget it", said Mulaire.
Images from inside the cathedral Tuesday showed its huge walls standing proud, with statues still in place and a gleaming golden cross above the altar.
Bertrand de Feydeau, vice president of preservation group Fondation du Patrimoine, told France Info radio that the wooden roof that went up in flames was built with beams more than 800 years ago from primal forests.
On Tuesday, the Vatican Culture Minister, Cardinal Gianfranco Ravasi, offered the Vatican's expertise in rebuilding Notre Dame, saying: "We have the type of know-how that the whole word recognizes as being of high quality, so I think an eventual future offer by the Holy See will be significant".
Plus said that now the fire is out "this phase is for the experts" to plan how to consolidate the edifice.
Firefighters declared success Tuesday in a more than 12-hour battle to extinguish an inferno engulfing Paris' iconic Notre Dame cathedral that claimed its spire and roof, but spared its bell towers and the purported Crown of Christ.
It was not yet known what caused the blaze.
"Nothing indicates this was a deliberate act", Heitz told reporters, adding that 50 investigators had been assigned to what he expected to be a "long and complex" case.
Tycoons and global firms have promised financial and expert help in rebuilding the 850-year-old cultural icon.
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