There isn’t any easy way to do this. You don’t want to traumatize people. Every effort is made to contact the next of kin for a death notification — if that can be done. People should not be identified as being dead until there is a positive identification of the body by visual or DNA methods. Only the coroner or medical examiner should announce the deaths.
The missing persons is much more difficult. With a mass evacuation, you don’t know if someone who has been reported as missing just has not been successful in getting in contact with their friends and relatives or if they really are missing and not just relocated somewhere.
Thus, authorities must post the names of those people known to be missing and hope that if they are alive, they find out that their name is on the list and they contact their friends or relatives first and then the authorities.