Around 8:15 am, fire-fighters were notified about a "gas leak" in a zone of the Belgian city of Ghislenghien,
approximately 50 km from Brussels. This leak on the 100-cm diameter gas pipeline (DN 1000) was evidenced by a loud
hissing, a tremor and the sudden creation of a cavity in the ground.
At 8:30 am, fire-fighters requested the assistance of the gas utility crew and set up a safety perimeter. Several tens of
workers were present on a plant construction site and in a number of neighbouring companies. The leak increased in
intensity, forming a whitish spray shooting some fifteen metres high.
At about 9:00 am, an explosion occurred; two minutes later, technicians were able to isolate the pipe segment between
the two sectional valves. The gas cloud ignited, producing a "fireball" that subsequently transformed into a long flare
whose height was estimated at 150-200 m. Depending on the estimation source, a temperature of around 3,000°C was
reached in the middle of the fireball.