At 7:49 p.m., the 19th-century spire that was the architectural masterpiece of Eugène Emmanuel Viollet-le-Duc and his post-Revolutionary restoration broke apart and fell through the nave. The bronze weathercock tumbled, taking with it three relics sealed inside in 1935.

It had been 66 minutes since the first flames were spotted.

The sky above the cathedral flamed orange, and the fire lurched toward Notre Dame’s iconic towers, then slipped inside.

As darkness fell, 20 firefighters climbed inside the two towers “at great risk to their lives, to attack the fire from the inside and save the building,” said Laurent Nunez, deputy interior minister.