They were last seen in a silver four-door Toyota Corolla with California plates 6BMU445.
Police said they believe Stone and the boy might have been heading to the airport, but police have not seen them there.
Porter Stone is white, 46 inches tall, 44 pounds, has a brown mohawk and was last seen wearing a white shirt and black and white shorts. He was carrying a backpack that says “ICU” and is filled with medical equipment.
Jeffery Stone, 33, is white, 6 feet 6 inches tall, 230 pounds, has a shaved head, and was last seen wearing a grey T-shirt, black shorts, and a San Francisco Giants baseball cap. He was also carrying a Nike backpack.
Police said they believe Jeffery Stone’s mother, Rhonda Marie Matthews, is traveling with them. She is 59, 5 feet 3 inches tall, weighs 130 pounds and has short, reddish-brown hair. She was last seen wearing blue jeans and a black Nike jacket.