The United Nations observed a minute of silence on Tuesday to mark the 30th anniversary of the Chernobyl accident. UN Secretary General Ban Ki-moon delivered a speech highlighting a necessity to remember the loss and suffering. 

On April 26th, 1986, a series of explosions occurred at the plant located 110 kilometers north of the Ukrainian capital of Kiev. It resulted in the demolition of the number 4 reactor, and a nuclear fallout across Ukraine, Belarus, Russia and some other European countries. The accident is the world's worst nuclear disaster to date. 

The World Health Organization estimates that 9,000 were killed by the disaster, while environmental group Greenpeace puts it at 90,000.