A fire has broken out in the famous French cathedral Notre Dame, destroying large sections of the landmark.
Social media is alight with pictures and videos of the blaze in the 850-year-old Paris landmark.
Smoke can be seen billowing out from the top of the cathedral. The main roof and spire of the cathedral has collapsed in the blaze.
The two towers at the front of the cathedral, as well as the wider structure, are believed to be safe from the flames.
There are unconfirmed reports a fire fighter has been injured while battling the blaze.
French president Emmanuel Macron declared a national emergency in the wake of the fire.
"Like all of my fellow citizens, I am sad to see this part of us burn tonight," he tweeted.
Macron cancelled his planned address to the nation to travel to the cathedral.
"Due to the terrible fire ravaging Notre-Dame-de-Paris, the President of the Republic has decided to postpone his speech," a spokesperson said.
A spokesperson from the cathedral said the entire building was burning.
"There will be nothing left. It remains to be seen whether the vault, which protects the cathedral, we be affected or not," local media were told.
The French Interior Ministry is also saying there is no guarantee the building can be saved.
The cause of the fire is not yet clear to fire fighters, but there is suspicion it could be linked to renovation work.
Local media report that police are treating it as an accident, but a Paris prosecutor has opened an investigation into the blaze.
Up to 400 fire fighters are believed to be working on the fire.
Paris Mayor Anne Hidalgo tweeted about the "terrible" fire.
"The fire brigade are trying to control the fire. We are mobilised locally in close connection with church authorities. I ask everyone to respect the security perimeter."
United States President Donald Trump suggested "flying water tankers" could be helpful.
"So horrible to watch the massive fire at Notre Dame Cathedral in Paris. Perhaps flying water tankers could be used to put it out. Must act quickly," he tweeted.
But the French civil defence agency has poured cold water on that idea, saying it would ensure the destruction of the building.
"The drop of water by air on this type of building could indeed result in the collapse of the entire structure."
National Party leader Simon Bridges is one of many international politicians to tweet about the blaze.
"I remember as a young man on my OE being in this building, very moved by its majesty. This is so sad."
The cathedral is one of the city's most famous attractions, drawing roughly 13 million visitors a year, and is the seat of the archbishop of Paris.
Its construction began in 1163 and wasn't completed until 1345.
However, it quickly became a jewel of gothic architecture, and hosted the coronation of Henry VI of England in 1431 as well as Napoleon in 1804.
During the French revolution it was used as a food warehouse, but now houses an array of art.
The church is also well known for featuring in the Victor Hugo classic novel The Hunchback of Notre-Dame, which was released in 1831.
The 1800s were a time of significant change for the cathedral, with architects brought in to do up the spire and renovate other sections which hadn't been looked after.
The renovations underway when the fire broke out included repairing broken gargoyles.