A woman walking her dog made the discovery shortly after dawn in Rosemont Park in the suburb of Rosemont.
The Sacramento County Sheriff's Department told KCRA-TV. Sacramento, homicide investigators were reviewing the cases of five missing girls to see if they were connected to the body. They were also combing yearbooks from area high schools to see if any photos matched the deceased.
Neighbors told KCRA the baseball field was in use until early Monday. They described Rosemont Park as a popular nighttime gathering place for teenagers.