What are the legal and appropriate things to do if you are 1st to discover an elderly family person has died?

Sorry that this is morbid, but I want to be prepared. My 87 year old father is in poor health and will die soon, which will be blessing for him. He is living at home, and wishes no heroic measures be taken to save him. A Do-not-resuscitate (DNR) form is completed and posted several places in his home. I am wondering what I should do if/when I visit (daily) and find him dead. Who can "declare" him dead? Do I call 911? The coroner? The police? He lives in California in case there are State specific rules on this.