President Trump on Monday mourned the fire that is engulfing the Notre Dame Cathedral in Paris, France, lamenting the destruction of what he called “one of the greatest treasures” of the world.

“That puts a damper on what we’re about to say, to be honest, because that is beyond countries, that is beyond anything,” the president said as he began a roundtable discussion on tax reform and the economy in Burnsville, Minnesota. “That’s a part of our growing up. It’s a part of our culture. It’s a part of our lives. That’s a truly great cathedral, and I’ve been there, and I’ve seen it.”

The president called the scene “terrible sight to behold," saying, “There’s probably no cathedral in the world like it. It’s a terrible scene,” Trump said.

The fire has been burning since 7 p.m in Paris, or 1:00 pm Eastern U.S. time.

A Notre Dame spokesperson warned that the damage would be severe. “Everything is burning, nothing will remain from the frame," said Andre Finot.

The cause of the fire is not yet known, although local media have suggested it could be “potentially linked” to renovations.

[Opinion: The US should pay 17.83% of Notre Dame's reconstruction costs]