At around 4 a.m., the Hofolding Volunteer Fire Department moved out after being alerted to a strong smell of gas. In the process, they checked several trucks in the area of the Aying parking lot on the A8.

There the task forces also found the culprit: a hazardous goods transport from the Netherlands was identified as the source of the smell. The truck was carrying odorant for gas networks. This is a foul-smelling safety additive that is often added to gases without a significant inherent odor and thus serves as a warning or alarm signal. The tractor-trailer had emptied its 30,000-liter tank in Italy and was now on its way back uncleaned. The driver took his legally prescribed rest break in the parking lot.

At around 8 a.m., while the facts were still being clarified, the Sauerlach and Brunnthal fire departments also reported that a strong smell of gas was perceptible in their municipal areas. Corresponding measurements were then taken to detect any explosive mixtures, but the results were negative. It is assumed that the cold east wind carried the stench from the highway to the communities six to seven kilometers away.

Since the morning, the hazardous materials monitoring team of the police tried to find a special company that could neutralize and dispose of the chemical. It was not until many hours later that a disposal company could be contracted to dilute and pump out the remaining odorant directly at the scene. Around 3:30 p.m., almost 12 hours after the start, the operation could be completed and the parking lot subsequently reopened.

After no leakage at the armatures could be determined, the articulated lorry was allowed to continue its journey. It is assumed that a small amount (less than one liter) had been missed when the tank was emptied. Allegedly, a small glass is sufficient with this odorant to spread the typical gas odor over a wide area.