The reactor explosion killed two of the reactor operating staff. In the emergency response that followed 134 firemen and station staff were hospitalized with acute radiation syndrome due to absorbing high doses of ionizing radiation. Of these 134 people, 28 died in the days to months afterward. Model predictions with the greatest confidence values of the eventual total death toll in the decades ahead from Chernobyl releases vary from 4.000 fatalities when solely assessing the three most contaminated former Soviet states to about 9.000 to 16.000 fatalities when assessing the total continent of Europe. It is considered the worst nuclear disaster in history and is one of only two nuclear energy disasters rated at seven—the maximum severity—on the International Nuclear Event Scale.