Early in the morning of Nov 1st 1970, a dance club in Isère had a really bad fire.
Club 5-7 had opened less than a year earlier and had become a popular regional venue.
There were still 180+ people partying at 1:40 am when a foam seat cushion caught fire from a cigarette or match.
The building had only one staircase, one exit (with a spiked full-height turnstile), and the fire doors were padlocked to prevent cheating. They didn't have a telephone line, either, so a manager had to drive into town to report the emergency.
The death toll was 146, including the members of the band Les Storms, and most of the managers. The corrugated roof melted; most of the bodies were too badly burned to be identified. Investigation later showed that the club had never had a final safety inspection as required by law.