In either case, the leaking tanker formed a cloud of gaseous propylene that partially entered the campsite and also drifted on the wind towards a discothèque to the northeast. The white cloud attracted the attention of campsite patrons, who approached the cloud with curiosity as it continued to spread. As the cloud began to permeate the crowded discothèque, it reached a spark, or other ignition source, and instantly flashed back into the tanker, causing a fire that almost instantaneously caused the weakened tank to explode and ignited the entire load of gas.