What agency is the first to call for disasters
what is the chain of command to call in a disaster?

First question's answer is: The Federal Management Emergency Agency is the agency that we first call for disasters through 911. On the second question which is, "what is the chain of command to call in a disaster", that would be led by the Incident Commander then next is the Public Information Officer, Site Facility Check, Search and Rescue teams, First Aid leaders and teams.