Notre Dame Cathedral fire: Cross remains, historic artwork and religious relics safe from damage

A cross remained inside the center of the Notre Dame Cathedral after a massive blaze heavily damaged the structure in Paris Monday night.

Photos began surfacing on social media showing the cross lit up as firefighters moved into the structure to assess the damage.

The centuries-old, gothic-style cathedral is also home to works of art. Paris Mayor Anne Hidalgo said most of the artworks were safely removed from the church. The country's culture minister, Franck Riester, tweeted photos of people loading the irreplaceable works onto trucks.

Riester also shared a video stating many parts of the "treasure" inside Notre Dame were now safe at Paris City Hall.

Dozens of religious relics were also saved from the blaze, and on Thursday, 16 religious statues were removed from the peak for the first time in more than 100 years to be cleaned.

The fire began late Monday afternoon and eventually caused a 315-foot spire to collapse, which at the time was part of a $6.8 million renovation. Paris fire commander Jean-Claude Gallet said two-thirds of the historic church's roofing was destroyed.

While authorities said the cause of the inferno is unknown, investigators began treating it as an accident based on preliminary information. Authorities were also investigating whether the construction was a factor in the fire.

The Associated Press contributed to this report.