The iconic spire at the top of the Notre Dame Cathedral in Paris has collapsed after a major fire broke out Monday. Video showed part of the roof of the cathedral collapsing into itself. The fire has since been extinguished.

By Monday evening, Paris fire chief Jean-Claude Gallet told reporters he believes that firefighters have managed to save the cathedral’s landmark rectangular towers from the blaze.

Gallet said, “We now believe that the two towers of Notre Dame have been saved,” the Reuters news agency reported. “We now consider that the main structure of Notre Dame has been saved and preserved.” There was still a risk that some of the interior structures could collapse, he said.

A deputy mayor of Paris, Emmanuel Gregoire, said the cathedral had suffered “colossal damages.”

Authorities have not yet released any information on the cause of the fire and said it would be investigated. The fire may potentially involve renovation work that has been carried out at the site, the fire service said. Extensive scaffolding covered a portion of the roof as part of the $6.8 million project before the fire broke out.

The Paris prosecutors’ office ruled out arson and possible terror-related motives, and said it was treating it as an accident, The Associated Press reports