Seveso disaster is a technological disaster. This disaster left a lot of lessons learned.
Disasters can be categorized into the followings; natural disasters, technological disasters, and human-made disasters.
The below is the outline and immediate effects of the disaster extracted from Wikipedia*.
The Seveso disaster was an industrial accident that occurred around 12:37 pm on July 10, 1976, in a small chemical manufacturing plant approximately 20 kilometers (12 mi) north of Milan in the Lombardy region of Italy.
Within days a total of 3,300 animals was found dead, mostly poultry and rabbits. Emergency slaughtering commenced to prevent TCDD from entering the food chain, and by 1978 over 80,000 animals had been slaughtered. 15 children were quickly hospitalized with skin inflammation. By the end of August, Zone A had been completely evacuated and fenced, 1,600 people of all ages had been examined and 447 were found to suffer from skin lesions or chloracne.
* We should confirm the facts.