TWO sisters who vanished for 44 hours after walking into woods near their home have been found alive in the rugged Northern California wilderness.

A desperate hunt has been on for eight-year-old Leia Carrico and her sister Caroline, five, who went missing after leaving their house in Benbow, California, at around 2.30pm on Friday.

A fire chief and firefighter from a local volunteer department found Leia and Caroline Carrico in a wooded area about one miles from their home, Humboldt County Sheriff William Honsal said.

But the girls, who left behind a trail of grenola bar wrappers, were "safe and sound" and uninjured, thanks in part to survival training they got with their local youth club.

Sheriff Honsal said: "This is an absolute miracle.

"This is rugged territory, this is an extreme environment. How they were out there for 44 hours is pretty amazing."

The girls had not been given permission by their mum to go for a walk together - but were believed to have taken off anyway.

Police were called at about 6pm and a massive search operation was launched after family and neighbours failed to track them down.

The search gathered pace on Saturday as the Coast Guard, the US National Guard and fire crews were drafted in to help.

Detectives have found boot marks in a wooded area near the girls' home - and distinctive granola bar wrappers that could help them be tracked.

Humboldt County Sheriff's Lt. Mike Fridley said the girls' mum had only just purchased the same brand - leading them to believe the sisters stocked up on snacks before vanishing.

On Friday he told SF Gate: "We have found some clues during the day that have made us change our directions.

"We found some granola bar wrappers and we were able to confirm with the mom that yes, these are granola bars that [she's] bought in the last few days.

"So the wrappers showed us a direction from where they started to where the wrappers ended at."