Casey was playing with two other children, and when those kids came inside without Casey, the grandmother and others spent 45 minutes searching before calling 911, authorities said, according to WCTI.
Sheriff Hughes said they will not stop until Casey Hathaway is found.
A 3-year-old boy who went missing on Tuesday has been found alive, surviving cold, rain and presumably critters in North Carolina's woods.
"Our number one priority is to find Casey", Craven County Sheriff Chip Hughes told reporters Wednesday.
"You have so many people volunteering from our community and surrounding areas because they were putting themselves in the shoes of the family", youth pastor Jonathan Ipock said.
"We're very thankful that you took the time out to come search for Casey and prayed for him", his mother, Brittany Hathaway, said at the press conference.
Three-year-old Casey Lynn Hathaway went missing around 1pm on Tuesday in the backyard of his grandmother's house in Ernul, a rural community ringed by forests and swamps.
Facing heavy rain, gusty winds and low visibility, rescuers and law enforcement combed the hard Craven County, North Carolina, terrain - focusing on up to 1,000 acres of heavily wooded areas.
Hathaway is at Carolina East Medical Center in New Bern being evaluated.
The boy authorities described as 25 pounds and 2 feet 4 inches tall was stuck out in conditions so bad that volunteers were turned away from the search.
The US Marine Corps also has also joined the search effort, Hughes said.
"We're not giving up", added the county's emergency management coordinator, Stanley Kite.
Authorities had been concerned that Casey wasn't adequately dressed for the cold temperatures.
'Additional search assets will return in the morning.
"Residents living in the area are asked to check storage sheds, vehicles, and their property for the child", deputies posted on Facebook.