Transcript for Fire nearly destroys Notre Dame Cathedral
I think we're all going to remember where we were when we saw the first images yesterday and we'll look now live at the notre dame cathedral, one of the most famous churches in all of the world. A sim blol of Paris, a site 13 million visited each year still standing after that devastating fire. Survived the French revolution and World War II and this fire as well but the flames destroyed so much. We saw that spire come down. The roof collapsed, as well. Here's what it used to look like inside and here's what it looks like right now. But there is a symbol of hope take a look. The cross on the altar still intact. Surviving the flames and the falling debris. Hundreds gathered to pray and sing last night and this morning the city of Paris is promising to rebuild as crews assess the extent of the damage. We're learning about incredible acts of heroism. Our foreign correspondent James Longman is there with the latest. Reporter: Good morning. This really was a catastrophic fire. Take a look behind me. All you see is sky above the structure there. That was where the roof was and it has entirely collapsed. All morning we've been seeing workers taking a look at the towers to make sure it is still structurally sound. But it really is a miracle this building wasn't more badly damaged. This morning, Paris, the city of lights, city dazed after a massive blaze ravaged historic notre dame cathedral. The more than 800-year-old heart of the French capital. Searing images as it glowed from within. You can see the gaping hole in its once majestic ceiling. French officials say the fire began at around 6:50 P.M. Local time but spread quickly. Just standing on our balcony you can smell it in the air. It's happening right in front of us. Reporter: Then this moment of horror. Notre dame's iconic spire crashing down, Paris, the world could only look on in despair. Part of the roof also collapsing. American student Kelly Weymouth took this of that moment. You started seeing parts of it fall off it. Everyone was like, it's going to come down. So people were records and I just happened to get the moment where it just collapsed and you can hear everyone just gasp. It was really, really sad. Reporter: Onlookers stunned. Some unable to hold back tears as the fire raged on. It smelled that it was old wood that was burning and the heat, I was 150, 200 meters on the opposite bank of the seine and you could just feel the heat coming off towards you. Reporter: Nearly 500 firefighters battling huge flames in a race to save what they could of the 13th century cathedral. The blaze engulfed scaffolding interest a $6 million renovation project. Investigators are looking into whether a construction worker could have accidentally sparked the inferno. By nightfall, five hours later the fire was contained and news came that the main structure and its iconic towers were safe but trepidation over what damage would be discovered inside. The cathedral is one of the most popular tourist destinations in the world attracting 13 million foreign visitors every year but this is the heart and soul of France. So now three hours later it's just sadness and despair. It's like a mother to me in a way so I really had the impression that my mother was being taken from me and I was very sad. And while firefighters were trying to beat the flames from outside, deep within the cathedral a human chain was formed to salvage priceless art and religious relics like the crown of thorns and the tunic of St. Louis. The mayor tweeting out this picture showing some of the works. French president Emmanuel macron addressing the crowd outside. This cathedral, we will rebuild it. Crowds gathered in prayer and song in this Easter week. Paris hopes its most cherished monument will rise from the ashes once more. ������ we are hearing some extraordinary stories of bravery this morning. Like, for example, the chaplain to the Paris fire brigade who last night rushed into that building to save some of the most important religious relics, this, by the way, was a man involved in saving people in the Bataclan attack in Paris and saved among other things, the crown of thrones -- the crown of thorns that Jesus wore as he ascended the cross. So there is a lot of hope here in Paris but a lot of work to do, of course, to rebuild it. $300 million or theres about has already been pledged including 100 million by Francois Pinault, the husband of Salma Hayek. All right, James, thank you.
This transcript has been automatically generated and may not be 100% accurate.