Authorities rescued a woman and her newborn baby after her family says she gave birth in a remote national forest in Northern California.

U.S. Forest Service spokesman Chris French said Tuesday that a helicopter pilot responding to a brush fire Saturday first spotted a mother and an infant. Rescue workers on the ground whisked the pair to safety and they were taken to a hospital, French said.

French said the cause of the fire is under investigation.

"I cannot confirm the day of birth beyond that she reported to us she had been there for three days," French said. "Also, her statement to us was that she gave birth at her vehicle within the forest. We did not witness the birth."

Amber Pangborn, 35, was released from a hospital on Monday, her mother said. The infant, Marissa, remains at the University of California, Davis medical center. The medical center didn't return a call inquiring about the infant's condition. Pangborn's mother, Dianna Williams, said the baby is "doing great."

Williams said the infant weighs about four pounds. Williams said Pangborn underwent gastric bypass surgery before the birth, a procedure that sometimes results in the birth of underweight infants.

Pangborn didn't return repeated phone calls Tuesday to her Paradise, California, home.

According to Pangborn's mother, her daughter was nine months pregnant and decided to visit an Oroville casino Wednesday to walk around in an attempt to induce labor. Williams said her daughter was traveling to another area casino when she ended up on a remote road in the national forest and ran out of gas. There was no mobile phone reception, Williams said. Oroville is about 80 miles north of Sacramento.

Williams said her daughter told her she went into labor early Thursday morning, unrolled a sleeping bag and gave birth in her car's backseat. Williams said Pangborn spent the next two days swatting away bees and insects, fearful of a bear attack. Mother and daughter survived on water and apples, Williams said.

On Saturday, Williams said Pangborn used a lighter, a can of hairspray and a can of oil to start a signal fire with the sleeping bag.

"She is smart and tough," Williams said. "I'm relieved it turned out all right."

French of the Forest Service said the fire burned about a quarter of an acre before it was extinguished.