Yu, who is described as an experienced hiker, never returned home from her day hike. Her car was found near Mt. Baldy Road in the Angeles National Forest, with her cell phone inside. The fear is that she may have fallen and injured herself:
Search-and-rescue teams, along with helicopters, search dogs and dozens of volunteers, have been out scouring the rugged terrain for any sign of Yu, even well into the night when temperatures have dropped below freezing.The area she was covering is described as a rough trek, but she's apparently pretty fit, and some food and water with her, so there's strong hope that she'll be found alive. More here: Rescue teams head into fourth day of search for missing hiker.
The search for Yu began Sunday after her roommate reported her missing.
"She really knows what to do. She's hiked up Mt. Whitney and all of these major mountains. That's her life," said John Gibson, Yu's roommate.
Authorities say they fear that Yu may have fallen and injured herself.