After a devastating fire nearly engulfed Paris’ iconic Notre Dame Cathedral on Monday, firefighters and officials are assessing damages.

Paris firefighters spokesman Gabriel Plus said the challenge Tuesday is no longer fire, but how the 850-year-old structure “will resist” or remain standing. The tragedy comes during Holy Week, an important event for the Catholic Church with Easter days away.

“The worst has been avoided, although the battle is not yet totally won,” said French President Emmanuel Macron.

Macron said a national fundraiser to restore the capital’s iconic landmark is underway Tuesday, and he called on the world’s “greatest talents” to help.

“No matter the destruction, the spirit of what it means to be a cathedral can and does survive such catastrophes,” Becky Clark, The Church of England’s director of cathedrals and church buildings, said in a statement.

More: Millions pledged to help rebuild Notre Dame Cathedral after devastating fire

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What caused the fire?

The cause of the fire is under investigation, but officials say it probably began as an accident during restoration work. The cathedral was in the midst of a $6.8 million renovation project. Arson was ruled out as well as possible terror-related motives, officials said.

Is the cathedral still burning?

After battling flames for more than 12 hours, firefighters said the fire was officially extinguished just after 9:30 a.m local time (3:30 a.m ET) Tuesday. Nearly 400 firefighters had battled the inferno.

More: 850-year-old Notre Dame survived the French Revolution. Here are 4 other things to know

Was anyone hurt?

Two policemen and one firefighter had been slightly injured.

How much of the building is damaged?

Paris Fire Chief Jean-Claude Gallet said the church’s main structure had been saved after firefighters prevented the flames from spreading to the northern belfry. The two iconic 69-meter (226-foot) bell towers remained intact. The cathedral’s spire and two-thirds of the roofing were burned, however.

The cathedral’s world famous 18th century organ with 8,000 pipes also survived, officials said. A relic known as the Crown of Thorns, which many believe was worn by Jesus Christ, also was spared. The religious statues that sat atop the cathedral were recently removed as part of the renovation.

More: Ancient treasures saved from Notre Dame inferno; firefighters battled tough odds

What’s next?

France’s public prosecutor said investigators would visit the Notre Dame site Tuesday to talk to the people who were working on the renovations to try to gather information about the cause of the fire.

French billionaire Francois Henri Pinault pledged $113 million toward reconstructing the cathedral and fellow billionaire Bernard Arnault and his LVMH group pledged $226 million.