The girl walked away from a large overnight camping trip at Huddart County Park, which covers around 900 acres of woodland, ravines and dense forest.
The girl was playing with friends at about 7:15 p.m. when she ran away from the area, San Mateo County sheriff's deputies said. Her parents were unable to find her and the child's mother called 911.
More than 75 officers and volunteers from the Sheriff's Office, the county parks department, a helicopter crew from the California Highway Patrol, and a search-and-rescue K-9 team joined the search effort, deputies said.
The helicopter crew — CHP officers Lennis Pope, the pilot, and Al Romero, the flight officer — saw a "faint light" in the woods, noted the location with GPS, and left the area to refuel the helicopter, Officer Jeff Moring said in a telephone interview.
When they returned, they could no longer see the faint light and so directed volunteers on the ground to that location, Mr. Moring said.
The girl was rescued around 11:30 p.m. that same night, deputies said. She had apparently become disoriented and was heading into a steep gorge, but was not injured and was taken to a hospital to be monitored for exposure.
A glow stick visible from a helicopter? The night vision goggles made the difference, Mr. Moring said. "Any light at all, (the goggles) are going to amplify," he said.
Lt. Ray Lunny of the Sheriff's Office disagreed, saying that the surrounding darkness of the park would have been sufficient to see the glow stick.
Bay City News contributed to this report.