Photographs Reveal the Extent of Damage Inside Notre Dame Cathedral

Smoke and flames rise from Notre-Dame Cathedral in Paris, France, on April 15, 2019. (Veronique de Viguerie/Getty Images)

The first heart-wrenching photographs have emerged of the damage done to the famed Notre Dame Cathedral in Paris by a devastating blaze.

From the outside, the imposing bell towers and outer walls, with their vast flying buttresses, still stood firm, but the insides and the upper structure were eviscerated by the fire.

This general view from the entrance shows smoke rising in front of the altar cross at Notre Dame Cathedral in Paris, France, on April 15, 2019, after a fire engulfed the building. (Philippe Wojazer/AFP/Getty Images)

French authorities have said the fire that tore through the structure was probably caused by accident.

Smoke billows as flames burn through the roof of the Notre Dame de Paris Cathedral in Paris, France, on April 15, 2019. (Fabien Barrau/AFP/Getty Images)

Prosecutors made the announcement on Tuesday, April 16, after firefighters doused the last flames in the ruins overnight.

Flames and smoke are seen as the interior of the Notre Dame Cathedral continued to burn on April 15, 2019. (Philippe Wojazer/AFP/Getty Images)

Investigators will not be able to enter the cathedral’s blackened nave until experts are satisfied its stone walls withstood the heat and the building is structurally sound.

Flames and smoke billow around the gargoyles decorating the roof and sides of the Notre-Dame Cathedral in Paris, France, on April 15, 2019. (Thomas Samson/AFP/Getty Images)

The fire swiftly ripped through the cathedral’s timbered roof supports, where workmen had been carrying out extensive renovations to collapsed balustrades and crumbling gargoyles, as well as the spire’s wooden frame.

Smoke rises in front of the altar cross at Notre-Dame Cathedral in Paris, France, on April 15, 2019 (Philippe Wojazer/AFP/Getty Images)

The Paris prosecutor has opened an investigation into “involuntary destruction by fire.”

Police on Tuesday began questioning the workers involved in the restoration, the prosecutor’s office said.

‘A Symbol of Our Country’

“The fire is fully extinguished,” fire service spokesman Gabriel Plus told reporters. “Our job today is to monitor the structure and its movements.”

“It’s a symbol of our country that risked being destroyed,” Culture Minister Franck Riester said.

Firefighters who entered the burning building saved many of its treasures, Riester said, although some paintings remained inside and risked smoke and water damage.

The Paris Hotel de Ville shows some of the artworks of Notre Dame de Paris rescued from the fire as the blaze devastated the cathedral, on April 16, 2019. (Thomas Samson/AFP/Getty Images)

There were many sculptures, paintings, and statues inside the cathedral that were at serious risk of damage.

‘Rose Window’ Trio Survives

A photograph shared on social media shows one of the cathedral’s three stained glass “Rose Windows” having survived the blaze intact.

The Archbishop of Paris said all three have been saved, according to CNN affiliate BFM TV.

Most of the cathedral’s precious treasures appear to have been saved.

“We managed to protect the most precious treasures in a safe place,” a Paris City Hall representative told CNN.

The fate of several items, including a fragment of the True Cross and one of the Holy Nails, is unknown.

A Challenging Blaze

Firehoses looked overmatched as flames raged across the cathedral’s wooden roof and burned bright orange for hours. The fire toppled a 300-foot spire and launched baseball-sized embers into the air.

Smoke billows as flames burn through the roof of the Notre Dame de Paris Cathedral on April 15, 2019, in the French capital Paris. (Fabien Barrau/AFP/Getty Images)

Hundreds of stunned onlookers had lined the banks of the Seine river late into the night as the fire raged, reciting prayers and singing liturgical music in harmony as they stood in vigil.

While the cause remains under investigation, authorities said that the cathedral’s structure—including its landmark rectangular towers—has been saved.

Firefighters continue to secure Notre Dame Cathedral in Paris on April 16, 2019, in the aftermath of a fire that caused its spire to crash to the ground (Stephane De Sakutin/AFP/Getty Images)

Some of the factors that made Notre Dame a must-see for visitors to Paris—its age, sweeping size and French Gothic design featuring masonry walls and tree trunk-sized wooden beams—also made it a tinderbox and a difficult place to fight a fire, said U.S. Fire Administrator G. Keith Bryant.

With a building like that, it’s nearly impossible for firefighters to attack a fire from within. Instead, they have to be more defensive “and try to control the fire from the exterior,” said Bryant, a former fire chief in Oklahoma and past president of the International Association of Fire Chiefs.

“When a fire gets that well-involved it’s very difficult to put enough water on it to cool it to bring it under control,” Bryant said.

Flames burn the roof of the landmark Notre Dame Cathedral in central Paris on April 15, 2019. (Francois Guillot/AFP/Getty Images)

It was too early to estimate the cost of the damage, said Bertrand de Feydeau of the Fondation du Patrimoine, a charity which works to protect French heritage, but it is likely to run into the hundreds of millions of dollars.

The construction of Notre Dame—which means “Our Lady”—began in 1160 and was, for the most part, completed a hundred years later.

The structure of the imposing cathedral has been modified several times since it was erected.

Reuters contributed to this report.