PARIS - The inferno that raged through Notre Dame Cathedral for more than 12 hours Monday destroyed its spire and its roof, but spared its twin medieval bell towers.
The exact cause of the blaze wasn't known, but French media quoted the fire brigade as saying it was "potentially linked" to a 6 million euro ($6.8 million) renovation project on the church's spire and its 250 tons of lead.
The Paris Prosecutor's office, which was investigating, said it was treating it as an accident.
Built in the 12th and 13th centuries, Notre Dame is the most famous of the Gothic cathedrals of the Middle Ages as well as one of the most beloved structures in the world.
Construction on Notre Dame — French for "Our Lady" — began in the 12th century and continued for nearly 200 years.
It sustained damage and fell into neglect during the French Revolution, but received renewed attention following the 1831 publication of Victor Hugo's novel "The Hunchback of Notre-Dame." This led to two decades of restorations, including the cathedral's famous flying buttresses and a reconstructed spire.
Aside from the structure, art experts were concerned about the fate of countless priceless artworks and artifacts inside.
The Crown of Thorns, regarded as Notre Dame's most sacred relic, was among the treasures quickly transported after the fire broke out, said Deputy Mayor Emmanuel Gregoire. Brought to Paris by King Louis IX in the 13th century, it is purported to have been pressed onto Christ's head during the crucifixion. Also saved was the tunic of St. Louis, a long, shirt-like garment from the 13th century, said Culture Minister Franck Riester.
The cathedral's famous 18th century organ that boasts more than 8,000 pipes also survived.
Some of the works were being transferred from City Hall to the Louvre, where they will be dehumidified, protected and eventually restored. A government official said the cathedral's greatest paintings would be removed starting Friday.
Much was saved in the interior too. The only major work damaged inside was the cathedral's high altar, installed in 1989 under Cardinal Jean-Marie Lustiger. It was hit when the spire collapsed, said Laurent Prades, heritage director for Notre Dame.
The three large stained-glass rose windows, among the most famous parts of the cathedral, were not destroyed, but might have been damaged by the heat and will be assessed by an expert.
French President Emmanuel Macron pledged to rebuild the beloved Roman Catholic architectural landmark, and wanted to see it completed within five years.
-The Associated Press