PARIS — With its iconic cathedral scorched but still standing, France on Tuesday launched an investigation into what triggered the Notre Dame inferno and how a fire that had probably started by accident could gut the symbol of a nation.

As the smoke cleared from the sky Tuesday, it was almost possible to look head-on at the church — to see its carved statues and two rectangular bell towers — and imagine that all was intact. Much of the valued art and relics had been saved. Even the exquisite stained glass windows remained in place, seemingly immune to the previous day’s flames.

But that belied the somber accounting of all that had been lost, and how the religious and architectural landmark at Paris’s center had been altered. The church’s trademark steeple, part of the Parisian skyline since the mid-1800s, had been swallowed in the flames. Char and smoke marks licked portions of the walls. And the roof — constructed with centuries-old wood — had been destroyed like tinder, leaving gaping holes that let sunlight shine into the cathedral Tuesday.

[Before and after: Notre Dame Cathedral scorched by blaze]

Officials warned that Notre Dame may still have gravely dangerous vulnerabilities, especially in the soaring vault. But a few government officials ventured inside, and camera footage showed charred rubble in front of the still-intact pews.

In an evening address to the nation, French President Emmanuel Macron described the firefighters as heroic, and said he hoped the country would reconstruct Notre Dame within five years — a more rapid timetable than that put forward by experts.

“We now have to get things done,” Macron said. “We will act, and we will succeed.”

He said the rebuilt cathedral would be “even more beautiful.”

[The fall of Notre Dame is a body blow to Paris and all it represents]

France’s interior minister said more than 500 firefighters had been mobilized Monday to help extinguish flames that had cloaked the sky in smoke. But questions remained about whether any warning signs had been missed.

Paris Prosecutor Rémy Heitz laid out a timeline in which a first alarm went off at 6:20 p.m., but no evidence of fire was found. Only when a second alarm went off — 23 minutes later — was fire detected.

“In the meantime, the church was evacuated because a Mass just started a bit earlier,” Heitz said.

A spokesman for the Paris prosecutor later clarified that it was church staffers, not fire fighters, who looked into the initial alarm.

Patrick Chauvet, the Notre Dame rector, told French radio that the cathedral’s “fire watchers” were on constant lookout and three times each day made “assessments” in the vulnerable area under the wooden roof.

“In terms of security, I doubt we could have done more,” Chauvet said.

[As flames engulfed Notre Dame, a fire brigade chaplain helped save the treasures inside]

“It was necessary to bring them out through the smoke,” Paris Fire Commander Jean-Claude Gallet told BFMTV. He said firefighters rushed into the chamber of the cathedral at the height of the fire to make the rescue.

The cathedral’s stained-glass rose windows, an ensemble that dates to the 12th and 13th centuries, are also likely intact, said André Finot, a cathedral spokesman.

“It’s a bit of a miracle. We’re very relieved,” he told BFMTV.

Vittorio Sgarbi, a Rome-based art historian, said that Notre Dame, even before the fire, had been an architectural mish-mash — some parts original, but many parts added or replaced.

“This is going to be a fateful event in the story of a non-authentic building, a sort of laboratory,” Sgarbi said.

[From the ashes of Notre Dame, a reminder that even in Europe, nothing is forever]

The effort was supported by Pope Francis, who on Tuesday called the fire a “catastrophe” and described on Twitter a desire that the damage would be “transformed into hope with reconstruction.”

On Tuesday morning, Paris Mayor Anne Hidalgo floated the idea of an “international donor’s conference” that would unite philanthropists and restoration experts in Paris to raise money for targeted purposes in rebuilding Notre Dame.

Many philanthropists needed little prompting. French luxury magnate François-Henri Pinault declared that his family would dedicate about $113 million to the effort. The family of Bernard Arnault, chief executive of the LVMH conglomerate and the richest man in Europe, pledged $226 million. The Bettencourt Meyers family behind L’Oreal matched that offer. Companies including Apple and the French oil giant Total made pledges of their own.

“I am not religious myself; I’m an atheist,” said Charles Gosse, 23, a business school student who launched an online funding campaign and quickly raised $27,000. “But this is beyond religion. It is a national monument like the Eiffel Tower and the Arc de Triomphe.”

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Today’s coverage from Post correspondents around the world

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