Officials believe the boy walked 300 yards from the site before he was found, KATV reported.
When they got to the car, deputies said they found the boy's 1-year-old brother awake and alert, still in his car seat, the AP reported.
Investigators think the 3-year-old was able to climb out of the wrecked car.
The children’s survival amazed rescue crews because the temperatures over the weekend were well into the 90s.
“Today is anything but short of a miracle,” Detective Nathan Greeley told KATV. “The 3-year-old and 1-year-old being able to survive in the elements ... it’s nothing short of a miracle, God’s blessing, that these children were able to survive this accident.”
The 1-year-old was taken to a children's hospital for treatment for dehydration, but officials said his condition is not life-threatening, the AP reported.