UPDATE: OCT. 14 AT 8:34 P.M.
The Missoula County Sheriff's Office says Andrea has been found and is safe.
UPDATE: Oct. 12 AT 12:29 P.M.
The Missing Endangered Person Alert for Andrea Anderson has expired; however, the Montana Department of Justice said she is still missing.
MISSOULA, Mont. - Law enforcement in Missoula are searching for a missing 13-year-old girl who was last seen Monday morning.
According to the Missing Endangered Person Advisory from the Montana Department of Justice, Andrea Anderson was last seen at 4 a.m., and may be in a green 1994 Chevy 3500 pickup truck with a long bed, silver wheels and an unknown license plate.
Andrea is described as white, standing 5-feet tall, weighing 100-pounds, has brown eyes and brown hair. She was wearing a pink hooded sweatshirt and black sweatpants.
The DOJ said she is emotionally unstable and was cutting herself when she ran away.
Anyone with information is asked to call the Missoula County Sheriff's Office at 406-258-4000 or call 9-1-1.