They need to be checking the homes (basements, closets, attics) of her friends and acquaintances in her age group.
I ran away from home at 13. I was gone for a week. The entire time, I was hidden out in a friends attic, less than a mile from my home. When the friends parents would leave for work during the day, I would come down into the main house. When they were home, I was secreted in the attic.
It probably would have lasted a lot longer before I was caught, except the friend hiding me couldn't resist the urge to skip school and her absence from school raised red flags and caused the police to come and search the house.
My prayers are with her family, who must be worried sick. I hope she is found soon and whatever triggered this rash and dangerous move can be resolved.