I can remember only two times in my life, at which my father hushed at me – and they were both in 1986. First one was in February, when the radio news announced that the Swedish prime minister Oluf Palme had been shot dead in Stockholm the night before. Second time was in April when the morning news warned of something even more alarming: The nuclear powerplant in Chernobyl had during the night had a serious accident of yet unknown scale.
The incident seemed to have went out of control very quickly, as this time line from the website www.chernobyl.info shows:
26 April 1986, 1:23:00: A test of the cooling system begins in unit no. 4 of the Chernobyl power plant
26 April 1986, 1:23:40: The emergency shutdown fails.
26 April 1986, 1:23:44: The reactor in unit no. 4 runs out of control and explodes.
A mere 44 seconds in time, but an uncontrolable situation of largely invisible danger; The disaster at Chernobyl is one of the grimmest moments in the history of machines gone wrong. The number of victims related to the Chernobyl accident is very diverse, with estiamtes from 56 to 90000 human lifes, but also trust in science, government and the good life was seriously wounded by what happened following that Saturday morning in 1986.

There are many many sources of information about Chernobyl on the internet and no list can be exhaustive. A few are:
http://www.chernobyl.info/index.php
http://www.chernobyl.co.uk/
http://en.wikipedia.org/wiki/Chernobyl_disaster
http://www.iaea.org/NewsCenter/Focus/Chernobyl/
http://www.chernobyl.com/info.htm
http://www.uic.com.au/nip22.htm