Authorities have described the child as a 5- to 7-year-old black male standing 3 feet 5 inches tall and weighing 60 pounds.
The boy has brown eyes, long black hair that is braided and was wearing a blue down jacket, white tank top shirt, beige pants and grey tennis shoes.
L.A. Police Department officers assigned to the Transit Services Division located the unattended boy around 7 p.m. A sign language interpreter unsuccessfully attempted to communicate with him.
Witnesses told police the child was with a woman at a cafe, and at some point, she just left him.
The child possibly has autism, according to officials. He was placed in the care of Child Protective Services.
If you have any information regarding the child or his parents, you're urged to contact the LAPD Transit Services Division at (213) 922-1410.