Horrified onlookers can be heard gasping in disbelief in a video that recorded the dramatic moment when the famed Notre Dame Cathedral’s spire collapsed in a fire.

In the clip, the top of the 91-metre-tall spire is seen falling off the cathedral and out of sight into a thick plume of smoke.

Kelly Weymouth shot the video from a boat she was travelling in not far from the 900-year-old cathedral.

“There it goes,” one person can be heard remarking while another woman exclaims “Oh my God!”

After 12 hours, firefighters managed to extinguish the raging fire and the extensive damage to the monument’s roof and spire was revealed.

Despite the loss of the spire, the cathedral’s iconic twin bell towers remained intact on Tuesday morning along with a number of priceless treasures, including an 18th-century organ and the purported Crown of Christ.