OAKLAND — The parents of a Rockridge teen who attends private school in Alameda spent the weekend combing the island for their 15-year-old daughter, who was last seen Friday night, the girl’s father said.

Elisabeth Griffith, a sophomore at Saint Joseph Notre Dame High School in Alameda, was last seen by someone at the campus about 6 p.m. Friday, ï»¿according to her father, Mike Griffith.

Oakland police on Friday opened a missing persons case, entered her information into the national database for missing children, and distributed fliers with her information to police in neighboring counties, officials said. Police described the girl as “at-risk” because of her age.

Friends and family have posted dozens of messages on the girl’s Facebook page asking her to return home. Her father said he and his wife have spent the last several days searching for their daughter, who suffers from depression and is without her medication.

“In normal circumstances she’s not the kind of kid who would be able to ignore (the pleas to come home),” he said.

Mike Griffith said the teen has taken off before but always returned home within a few hours. He said he has never filed a missing persons report before.

The girl had plans to go shopping with a friend on Friday after school but when class let out at 2:40 p.m. she was not on campus, he said. “We are amazed that she would stay away for this long,” he said.

Elisabeth is Latina, 5 foot 2, 140 pounds with long black hair and brown eyes. She was last seen wearing a black sleeveless T-shirt with a Ramones logo on it and black and white patterned leggings. A witness told police they had seen a girl wearing similar leggings Monday morning in West Alameda, but officers did not find the girl.

Her father said she does not have an ATM card, money or a cell phone, but could be staying with family of her 15-year-old boyfriend. Contacted on Tuesday afternoon, the boy declined to speak about the girl, other than to say he does not know her whereabouts.

Contact Kristin J. Bender at kbender@bayareanewsgroup.com. Follow her at Twitter.com/kjbender.