The fire at the Lubrizol factory, a company that makes specialty chemicals, began around 2:40 p.m. local time Thursday.
Around 200 firefighters started to tackle the dangerous blaze, which took them several hourse to put out.
The fire did not cause any casualties or injuries among the 400 employees of the plant, according to local authorities, however, Rouen residents posed questions of serious concern on social media and frustration about the poor response by officials to the burning chemicals used as additives to petroleum fuel. Citizens of the French city said that all government officials were more interested in reacting to the death of former President Jacques Chirac, who passed the same day.
The regional governor ordered all schools to be closed and for residents of the Rouen area, comprising a dozen municipalities, were recommended to stay at home.
Authorities claimed that they have not detected either "acute toxicity" or "danger" yet, but recommended that residents in affected areas "wash their hands" and "fruits and vegetables" from local harvests.
The origin of the fire remains unknown. The health ministry announced that it asked local authorities to launch an investigation.
The same factory was the subject of another accident on January 21, 2013 that resulted in the leak of a gas named mercaptan, whose smell could be perceived by people as far away as England.
The factory was sentenced to pay a US$4,200 fine in April 2014, after being found guilty of "negligence" that caused the leak.