On the day of the 16th anniversary of the disaster at the Chernobyl nuclear power plant, Ukraine's leaders honoured the memory of heroes who died when eliminating the consequences of the accident on that Ukrainian station. They observed a minute of silence in memory of the heroes. Salvoes were fired, honorary guards marched solemnly and fire-engines passed honking in their honour. The accident took place at 1.24 hours on April 26, 1986, with an explosion destroying the No.4 reactor. According to scientists' estimates, the amount of radioactivity released totaled 50 million curies, or the equivalent of 500 atomic bombs of the type dropped on Hiroshima in 1945. The disaster, which became global, contaminated 50,000 square kilometres of territory in Ukraine, hitting 12 out of Ukraine's 25 regions. Casualties numbered 3.2 million people, including about 1 million children.