Authorities spent Wednesday evening searching for the 33-year-old actress at Lake Piru in California's Ventura County and fear she may have drowned after her 4-year-old son was found sleeping alone on board a pontoon boat that had been rented three hours earlier. The boy was wearing a life-vet. An adult life-vest was also found on board. A dive team and air unit were deployed to search for Rivera. The search was suspended late Wednesday with plans to resume at daybreak. The Ventura County Sheriff's Department said it responded to a report of a boy alone on a boat at about 4:48 p.m. Rivera rented the boat at about 1 p.m. and had an afternoon swim with her son. Ventura County Sheriff’s Department Capt. Eric Buschow said the boy got back onto the boat after the swim but his mother did not follow. “He’s in good health,” Buschow said of Rivera’s son, adding: "The family is going through a very traumatic time right now.” On Tuesday afternoon, Rivera tweeted a picture of her and her son with the caption: "just the two of us." Rivera is best known for portraying Santana Lopez on six seasons of Glee. Recently, she starred on Step Up, which Starz picked up for a third season in May.