The incident was reported at 7:45 a.m. at a mostly empty lot near the intersection of Bixel and Sixth streets, just west of the 110 Freeway, according to the Los Angeles Police Department.
Firefighter-paramedics were summoned to the scene, and "upon further investigation and assessing the patient she does not mention any injuries and is not in distress," the Los Angeles Fire Department said in a statement.
Video from AIR7 showed more than a dozen firefighters and police officers standing over the entrance to the subterranean tunnel, and a ladder was lowered into it.
The extraction operation was ongoing two hours after the woman was initially reported to be inside.
She was provided with a yellow safety helmet and placed in a harness that was tied to a fire engine's aerial ladder.
Shortly before 10 a.m., the woman was slowly hoisted out of the hole as emergency responders guided her to safety.
She was taken into custody and transported to a hospital for a mental evaluation, an LAPD spokesperson said.