The incident occurred in a pharmaceutical plant. A disk ruptured on the vent of a reactor and the reaction mixture was projected onto a frontage of the synthesis workshop. It caused a spill of 700 l of a mixture of monochlorobenzene (which is flammable liquid) and sodium borohydride (which is toxic). The plant operator manually activated the emergency response plan, evacuating the personnel. The internal emergency services set up a foam blanket on the spill, then carry out a water washing. The discharge valves were closed and the product was recovered in the fire retention basins. The site's response teams marked out the impacted area and took VOC measurements. Two hours later, the plant operator lifted the emergency response plan and set up a restriction zone around the building. Nine employees were slightly affected by odoursThe immediate cause was the formation of amount of hydrogen which could not be vented.