People in Hiroshima/Nagasaki of that era had and those who lived still have DNA damage. Cancers come from radiation and many die sooner or have died later from cancer. Life stops at the day of the blast. There is little help, no food, no safe drinking water nothing. Hiroshima killed 20,000 immediately. Nuclear weaponry in present time will kill millions instantly leaving the rest to suffer seemingly to the end of time.
The blast Youtube: