A spokesman for Paris police tells CNN the Notre Dame fire is now under control.
The fire burned for several hours Monday, causing the collapse of the cathedral's iconic spire and the destruction of its roof structure, which dated back to the 13th century.
Consumed by flames, the spire leaned to one side and fell onto the burning roof as horrified onlookers watched.
French President Emmanuel Macron praised firefighters for saving the cathedral's iconic facade and towers. "Thanks to their bravery, the worst has been avoided."
Paris Mayor Anne Hidalgo said in a tweet that major art pieces and sacred items from Notre Dame were saved from the fire.
"Thanks to the @PompiersParis, the police and the municipal agents," Hidalgo tweeted, "the Crown of Thorns, the Tunic of Saint Louis and several other major works are now in a safe place."
The cathedral is home to numerous artifacts, works of art and religious relics, each telling a story.
After the devastating fire tore through the cathedral on Monday, toppling its spire, many feared the items -- collected over the centuries -- might be lost. It was unclear how many had been saved.
Click here to take a look at some of the most famous items that the Paris cathedral is home to, including several sacred artifacts, including the Crown of Thorns, a fragment of the "true cross" on which Jesus was crucified, and one of the nails used by Romans to crucify Christ.
The former US first lady, who is in Paris for her book tour, has tweeted about the "majesty" of the cathedral, which is one of the city's most recognizable and visited attractions.
Michelle Obama writes that the "history, artistry, and spirituality" of the famed cathedral "took our breath away, lifting us to a higher understanding of who we are and who we can be."
She signaled her commiseration with the people of Paris, but expressed confidence that it would soon be rebuilt, to "awe us again."
While the cathedral's two towers were saved, its spire collapsed in the massive blaze that engulfed the world-famous building. Watch the moment it came down here.
The fire at Notre Dame Cathedral “goes beyond Paris,” Archbishop Michel Christian Alain Aupetit told CNN.
“I received a supportive message from the chief rabbi of Paris. Everyone is writing in to share their feelings. This goes beyond Paris. People are reacting worldwide,” Aupetit said.
“The young people behind me show the power of faith, the power of a message of peace,” the Paris archbishop added.
Foreign Minister Mevlut Cavusoglu said Turkey is following news of the fire at Notre Dame cathedral in Paris with “great sadness,” according to his official Twitter page.
“The destruction of this architectural masterpiece of world heritage is a disaster for all humanity,” Cavusoglu wrote in French on the social media site.
Notre Dame’s medieval roof structure, known as "the forest," has been lost to the massive fire, according to Msgr. Patrick Chauvet, the rector of the cathedral.
“The framework from the 13th century is called a forest, because it required a forest of trees to build it,” he said.
The cathedral's wooden frame, which primarily consists of oak, contains beams that date as far back as the first frame. It features trees cut down between 1160 and 1170, forming one of the oldest parts of the structure.
Most of the current frame dates from the year 1220, according to the church's website.
According to the Notre Dame website, it’s one of Paris’s oldest frameworks. Learn more about the construction of the famous cathedral here.
Former vice president and potential 2020 Democratic hopeful Joe Biden tweeted his thoughts on the blaze, which consumed large sections of the cathedral.
"For centuries, Notre Dame Cathedral has withstood wars, revolutions, and the test of time," the tweet reads, noting that the devastating fire occurred during Holy Week, the holiest week of the Catholic calendar. Biden calls it "a symbol of faith & a testament to history," adding that he believes it will be reconstructed, to "rise again."
The Paris prosecutor’s office has opened an investigation into the devastating fire at Notre Dame Cathedral, a spokesperson told CNN on Monday.
Prosecutors will be investigating an "involuntary destruction by fire,” the spokesperson said.