A 47-year-old East Bay woman drowned Sunday evening at Cowell Ranch State Beach south of Half Moon Bay after having gone into the water to try to save three children swept away by an undertow, a San Mateo County Sheriff’s detective said.

The sheriff’s office and the California Department of Parks and Recreation were called at 7:17 p.m. about the drowning. San Mateo Sheriff’s Detective Rosemerry Blankswade said the woman, whose name wasn’t made public tonight, was taking pictures of young family members when an undertow carried three kids out into the waves.

The woman then went into the ocean to try to save the children, but got swept out into the water herself, Blankswade said. Other family members saved the three children, but couldn’t bring back the 47-year-old woman.

The woman’s body was eventually swept back to shore, Blankswade said, and CPR was performed, but she could not be revived.

The California Department of Parks and Recreation, which oversees Cowell Ranch State Beach, is heading the investigation into the woman’s death.