Two security guards at the cathedral told police they noticed the flames for the first time only when the flames were already almost 3 meters high at 6:43 p.m. local time (12:43 p.m. ET), indicating the fire alarm sensors might not have been working properly, the police source told CNN.
The first alarm rang at 6:15 p.m. local time. An alert flashed on the Notre Dame security control screens showing which sensor was sending the alert.
According to the police source, the two security agents went to check the location but didn’t see anything at that time. When the second alarm rang at 6:43 p.m. local time, the two security agents followed the alarm system instructions and went to another location at the top of the cathedral, where they then saw the flames.
Investigators have pinpointed the start of the fire that ripped through Notre Dame Cathedral on Monday, a police source told CNN.
After police reviewed a cache of amateur video and photos from local residences, investigators believe the fire started at the center of the cathedral’s roof towards the base of the iconic spiral, the police source said.
The police source also told CNN that investigators are focusing on two potential problems relating to the outbreak of the fire. One issue under investigation is a possible problem with the fire alarm system sensors.
Investigators’ second line of inquiry, the source said, relates to the elevators that were built for the construction workers. The source provided no additional details on that.