A 12-year-old girl drowned and her 9-year-old sister was in serious, but stable condition Sunday after they were found alone and unattended, in the ocean at Pokai Bay Beach Park. The younger girl was found drifting just after noon in shallow water. She was brought to shore and transported to the hospital in serious, but stable condition. About a half hour after that, the girl's 12-year-old sister was seen submerged in the same area. She was taken to a hospital in critical condition and died there later. Witnesses told authorities that the girls' father left them unattended at the beach. It is suspected that the older sister was trying to help her younger sister.