PHILADELPHIA, Pennsylvania -- A 15-year-old girl is under arrest following the death of her newborn son, who police say was found in a Philadelphia dumpster.Police say a woman approached officers around 10:30 p.m. Monday.According to investigators, that woman told police her daughter's friend placed her newborn son inside a dumpster.That woman said she went to the dumpster, retrieved the baby, then notified police.The baby was taken to Temple University Hospital but was pronounced dead a short time later.Police say they found the teen, and her mother, inside her home. Investigators believe that's where the teen gave birth.The teen and her mother were taken to the Special Victim's Unit. The teen girl was placed under arrest and was taken to Temple University Hospital for precautionary medical treatment.Homicide detectives are now investigating.The names of those involved have not been released.