A fire broke out Thursday in the spire of the cathedral in northern French city Rouen, its mayor said, sharing a photo of a column of smoke rising from the Gothic landmark.
The fire's "origin is unknown at this point," mayor Nicolas Mayer-Rossignol posted on X, adding that "all public resources are mobilised" to fight the fire.
Local fire service SDIS76 said the alarm was raised around midday (1000 GMT) and that 33 vehicles and 63 firefighters were on the scene.
"Fire broke out at the tip of the spire, which isn't made of wood, but rather metal," the prefecture of the Seine-Maritime department told AFP.
The monument is "currently undergoing restoration work," it added.
It was not immediately clear whether the wood frame of the spire was ablaze.
Fire in the wooden frame of the roof was behind the massive 2019 damage to the world-famous Notre Dame cathedral in Paris, where repairs are only now nearing completion.
The Our Lady of the Assumption cathedral has been evacuated and a security perimeter set up, the prefecture said.
People should "stay away to give space for emergency responders to work," it added.
Construction began on Rouen's cathedral in the 12th Century, according to its website, with work lasting several centuries until it achieved its present form.
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