People have been sharing videos and photos of fire and smoke plumes above the Notre-Dame Cathedral in Paris.

Firefighters told Huffington Post France the fire started in the building's attic and was "potentially linked" to renovations.

The cathedral is one of Paris's most famous monuments and has been standing for centuries.

The Notre-Dame Cathedral in Paris caught fire on Monday, causing major damage to the centuries-old building.

Early Tuesday morning the fire was contained, police officials in Paris said, according to CNN. While the iconic spire collapsed due to the fire, the cathedral's twin towers are reportedly safe, French officials said.

President Emmanuel Macrontweeted a message of rebuilding on Monday night: "We will rebuild it. All together."

Macron had been scheduled to deliver a major speech on Monday, announcing policy plans in response to a national debate (the "Great National Debate" held online and in person) and the yellow vest movement. The speech was postponed, however, as Macron headed to the scene of the fire.

"The fire is now weaker," Junior Interior Minister Laurent Nunez told reporters on the ground in Paris. "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."

The Paris Fire Brigade commander general Jean-Claude Gallet said one firefighter was injured, according to CNN.

Roughly 400 firefighters have been "mobilized," Nunez tweeted, also saying "the fire has declined in intensity."

It remains unclear how the building caught fire, but emergency responders and firefighters were on scene and urged people to stay away from the area.

The cathedral's spire that stretched nearly 300 feet in the air collapsed.

Notre-Dame spokesman Andre Finot said the entire wooden interior of the landmark would likely be destroyed.

"Everything is burning, nothing will remain from the frame," he said.

France's Interior Ministry said firefighters might not be able to save the structure at all, the Associated Press reported.

A spokesman for the Paris prosecutor told CNN that it has launched an investigation into the blaze.

The fire broke out at 6:50 p.m. local time on Monday, the start of Catholic Holy Week, a Notre-Dame spokesperson told the French-language website, Le Figaro.

The fire was "potentially linked" to renovations in the building, firefighters told Huffington Post France.

The cathedral was in the midst of a 6 million-euro ($6.8 million) project to repair the building's spire, the Associated Press reported. That renovation was part of a larger $150 million euro ($169 million) restoration project.

The New York Times spoke to cathedral spokesperson André Finot, who said the fire was started in the spire of the cathedral. The cathedral is constructed primarily of limestone — a flammable stone — and has a roof made from wood. The Notre-Dame had previously been referred to as a "forest" because of the more than 13,000 oak trees that were cut to construct its roof.

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Paris Mayor Anne Hidalgo called the fire "terrible" in a tweet about the blaze. She said officials were working to control the flames and asked everyone to respect security blocking off the area.

The cathedral is one of Paris's most famous monuments and has been standing for centuries. The medieval structure was completed in the 12th century and is one of Paris's most popular attractions.

The building, which was featured in Victor Hugo's classic novel "The Hunchback of Notre-Dame," welcomes around 13 million visitors a year.