On 21 September 2001, an explosion occurred at a fertilizer factory in Toulouse, France. The disaster caused 31 deaths, 2,500 seriously wounded, and 8,000 light injuries. The blast (estimated yield of 20–40 tons of TNT, comparable in scale to the military test Operation Blowdown) was heard 80 km away (50 miles) and registered 3.4 on the Richter magnitude scale. It damaged about 30,000 buildings over about two-thirds of the city, for an estimated total cost of about €2 billion.