French prosecutors have said the fire that tore through the world famous Notre Dame Cathedral was probably an accident as they have found no evidence of arson so far.
The investigators are working on the assumption the inferno was accidental.
About 50 police officers are working on the probe and have been questioning 15 workers involved in renovations to the cathedral's roof, where the fire broke out.
Paris prosecutor Remy Heitz told reporters on Tuesday that the investigation will be long and complex as they will not be able to enter the cathedral until experts have checked its stone walls and the building has been made structurally safe for inspection.
Experts say damage from the heat, which reached more than 800 degrees Celsius, and from the vast quantities of water that firefighters poured into the cathedral, needs to be assessed.
"All in all, the structure is holding up well but some weak points have been identified, especially around the vault, meaning the ceiling, and also on one of the gable ends of the north transept that has to be secured, which has led to the evacuation of five residence buildings."
After the police and fire services spend 48 hours assessing the security and safety of the cathedral, experts will enter it to retrieve some of the many treasures that are stored inside.
Hong Yoo, Arirang News.