Fire at Notre Dame Cathedral

5:53 p.m. ET, April 15, 2019

Mass was being celebrated at the cathedral when the fire broke out, attendee says

French-American François-Xavier Lochet, 70, was attending Mass at Notre Dame Cathedral on Monday when a loud alarm went off just as the congregation began the Universal Prayer -- it was so loud Lochet could barely understand the messages in French and English.

Most of those who heard it, however, just stood there as visitors began to be ushered out of the cathedral. That was until, Lochet said, a police officer approached a priest and told him, "This is no joke. You've got to get out."  

Lochet began walking back to his mother's home when he turned around and saw smoke.

"Nobody was paying attention," he said. "I stopped and I took my phone out and I waited."  

Soon, smoke began billowing out from the cathedral.

"To me. I felt like crying," he said. "This is my most favorite church probably in the world. To me, as a kid, I climbed the towers when I was 12 years old."

He could not help but think about the countless craftsmen who devoted their entire lives to constructing the church, even those who helped renovate it. He'd often go to Mass, or just to listen to the cathedral's organs.

"It's a huge piece of history of Europe," he said. "Gone."

He took this photo of the early flames. That spire, and much of the roof on which it sat, would later fall:

5:31 p.m. ET, April 15, 2019

A growing crowd of mourners are singing hymns and praying outside Notre Dame

ERIC FEFERBERG / AFP/GETTY IMAGES
ERIC FEFERBERG / AFP/GETTY IMAGES

It's past 11 p.m. in Paris, but the crowds of Notre Dame mourners haven't gone anywhere -- many are still gathered outside the cathedral, praying and singing hymns.

Some are on their knees; at one point, a group broke out in a haunting rendition of the "Ave Maria."

They have been singing for almost two hours now, and the hymns are getting louder as more people join in.

Watch the scene here:

5:25 p.m. ET, April 15, 2019

NOW: French official says "both towers of the cathedral are safe" and the fire is cooling

ERIC FEFERBERG/AFP/Getty Images
ERIC FEFERBERG/AFP/Getty Images

Both towers of the Notre Dame Cathedral “are safe,” said Laurent Nunez, secretary to the interior minister, hours after a massive fire toppled its spire, burned most of its roof and threatened the centuries-old art and architecture inside.

“The fire is now weaker. We are now in a time of cooling but both towers of the cathedral are safe. We're still working to save the cathedral's work of arts," Nunez told reporters at the scene.

One firefighter has been seriously injured, said Paris Fire Brigade commander general Jean-Claude Gallet. Gallet said that two-thirds of the roof has been destroyed.

5:26 p.m. ET, April 15, 2019

Here's why Notre Dame Cathedral is so important to Catholics worldwide

FRANCOIS GUILLOT/AFP/Getty Images
FRANCOIS GUILLOT/AFP/Getty Images

This week is Holy Week, when millions of Western Christians mark the death and resurrection of Jesus. Under normal circumstances, Notre Dame Cathedral in Paris would have been preparing to display its holy relics to the faithful on Good Friday.

But as fire engulfed the sacred site on Monday, Catholics across the world reacted in horror and disbelief, particularly when the cathedral's iconic spire toppled amid the flames.

For generations, Notre Dame has been a place of pilgrimage and prayer, and, even as religion in France has declined for decades, it remained the beating heart of French Catholicism, open every day for Mass.

About the cathedral: Notre Dame is not a parish church, meaning that it does not have a regular body of worshippers who "belong" to the church. But it is still the home church of Paris Archbishop Michel Aupetit, and draws Catholics for vespers (evening prayers), Masses and the Sacrament of Reconciliation, also known as Penance.

And every year during Holy Week, Notre Dame unveils some of the most coveted relics in Christendom. Among them is the Holy Crown, believed by many to be from the crown of thorns placed on the head of Jesus. Catholics have prayed with the Holy Crown for more than 16 centuries, according to the cathedral.

Notre Dame counts among its treasures two other relics connected to Holy Week: a fragment of the Wood of the Cross, believed by many to be a part of the "true cross" on which Jesus was crucified; and one of the nails that the Romans used to crucify Jesus.

Keep reading.

5:26 p.m. ET, April 15, 2019

Obama: We mourn when history is lost -- but we also rebuild

Former US President Barack Obama just tweeted about the destructive fire at Notre Dame Cathedral in Paris.

"Notre Dame is one of the world’s great treasures, and we’re thinking of the people of France in your time of grief. It’s in our nature to mourn when we see history lost -- but it’s also in our nature to rebuild for tomorrow, as strong as we can," he said.

4:25 p.m. ET, April 15, 2019

UN chief: "Horrified by the pictures coming from Paris"

UN Secretary-General António Guterres said he is "horrified" to see the images coming out of Paris.

"Horrified by the pictures coming from Paris with the fire engulfing Notre Dame Cathedral — a unique example of world heritage that has stood tall since the 14th century," Guterres said in a tweet. "My thoughts are with the people and government of France."

5:27 p.m. ET, April 15, 2019

Next hour and a half will be crucial to saving Notre Dame, firefighter says

GEOFFROY VAN DER HASSELT/AFP/Getty Images
GEOFFROY VAN DER HASSELT/AFP/Getty Images

The next hour and a half will be crucial to efforts to save what remains of the Notre Dame Cathedral, said Jean-Claude Gallet, commander general of the Paris Fire Brigade.

“There’s a risk that the great bells fall. If the bells fall, it’s the tower that collapses. There are firefighters inside and outside. The next hour and a half will be crucial,” he told reporters on the scene.

“We need to win this battle and block the spreading of the flames. The most efficient action is from the inside. We are not sure if we will be able to stop the spreading of the flames to the North Tower," he said.

He said the initial call to emergency services notified authorities of a fire in the attic of the cathedral, although the cause of the blaze is unknown.

“We are evacuating the most precious artwork that is being sheltered,” Gallet said.