Officials in France are investigating whether the Notre Dame fire was caused by an electrical short-circuit.
The cathedral suffered significant damage in the blaze on Monday, including the destruction of its spire.
Associated Press today quoted a police official as saying investigators believe a short-circuit was the most likely cause of the fire.
However, investigators still haven't gained full access to the cathedral due to safety concerns and ongoing efforts to add support planks to fragile areas.
Following the fire, focus has largely shifted to plans to restore the building - with French President Emmanuel Macron saying he wants the work completed by 2024.
Around €900 million has now been donated to rebuild the destroyed sections of the iconic cathedral.
With several years of work likely required before Notre Dame can reopen, a temporary wooden structure for worshippers has been proposed for the large area in front of the cathedral.
Speaking on French television and quoted by AFP, Notre Dame’s chief priest Monsignor Patrick Chauvet said: "We mustn't say 'the cathedral is closed for five years and that's it'.
"Can I not build an ephemeral cathedral on the esplanade (in front of Notre-Dame)?"
He suggested the mayor of Paris, Anne Hidalgo, had already backed the idea.
This afternoon, the mayor was among the Parisians who gathered to pay tribute to the firefighters and others who helped save the cathedral.
— Anne Hidalgo (@Anne_Hidalgo) April 18, 2019
Ms Hidalgo thanked firefighters for 'saving a part of ourselves' during the dangerous operation.
Authorities have previously indicated that the building was saved during a crucial '15-30 minute' period on Monday.
The French government has already confirmed an international architecture contest will be launched to determine how the damaged roof and spire would be rebuilt.