The deaths of three children on a Coney Island beach have been ruled homicides, the medical examiner’s office in New York City said Tuesday. The children, a boy and two girls, were found unconscious on the sand before 5 a.m. Monday. Efforts to revive them were unsuccessful, police said, and their mother was found soaking wet nearby. Julie Bolcer, a spokeswoman for the Office of the Chief Medical Examiner, confirmed Zachary Merdy, 7; Liliana Merdy, 4; and Oliver Bondarev, 3 months old, all died from drowning. Police said Tuesday that no one had been charged over the matter and the investigation was ongoing. A police source told the New York Daily News that the children’s mother, Erin Merdy, called a cousin and confessed to drowning her kids. Police are investigating whether postpartum depression is a possible motive, according to ABC News.