At around 12.25 pm, an explosion followed by a fire fuelled by flammable products occurred in the research laboratory of a chemistry school causing the death of a professor. Thick black smoke was released above the building. According to a witness, a number of particles fell to the ground. The district was sealed off and a school was evacuated. The first level of the emergency plan was activated; 157 firefighters, 64 gendarmes (French military police), 40 police officers, 2 state security police companies, a helicopter and a SAMU (French emergency services) team were mobilised. Dedicated to industrial risks, this laboratory, inaugurated in 1977, was installed on the 25 ha university campus, in a 3-storey building. The explosion damaged the building and a number of windows were shattered. Firefighters contained the fire at around 3 pm then removed the rubble (collapsed floors).

The situation was alarming: one 41-year old teacher who was standing above the laboratory was killed, probably due to falling objects. Seriously injured, an 18-year old trainee student in the premises had to be place in intensive care, her condition was considered serious. Around twelve slightly injured people were hospitalised: 2 in a state of shock, 10 victims of shards of glass, the others suffering, in particular, from hearing problems following the explosion. A psychological assistance unit open 200 m away took in approximately 250 students close to the building at the time of the incident.

The chemical substances and radioactive sources stored in the building that had been ripped apart were removed, and a specialist company secured the building. Investigators discovered a 1.5 m high cylinder of ethylene intact at the epicentre of the explosion and entrusted it to legal experts. A leak from the cylinder (not resealed?) caused the accident. An injured laboratory scientist was charged with involuntary manslaughter and injury; on 25/11/2010, he was sentenced by the Correctional Court of Mulhouse to an 18-month suspended prison sentence and a fine of 8,000 euros.