Ukrainians held candlelit vigils Tuesday to mark 30 years since the world's worst nuclear accident at Chernobyl spewed radiation across Europe and left several thousand people dead or dying. Church bells rang and mourners laid flowers at Chernobyl's memorial square as the clock turned 1:23 am -- the moment the plant's reactor number four exploded and changed the fate of a generation living across the former Soviet Union. At least 30 people were killed on site and several thousand more are feared to have died from radiation in what Ukrainian President Petro Poroshenko said "appears to have been the world's largest man-made catastrophe".
