A Rio Vista Fire Department water unit is searching for three people missing in Delta Sunday afternoon. Courtesy of Rio Vista Fire Department/ A child was able to swim ashore in the Sacramento-San Joaquin Delta, but three adults remained missing Sunday afternoon after an afternoon accident, officials said. Sacramento County Sheriff’s deputies received a call about a possible drowning at Brannan Island State Recreation Area at 1:30 p.m. Upon arrival they said the child was out of the water and did not need medical attention. However, three adults who were with the child are missing, according to Sgt. Rod Grassmann, public information officer for the Sheriff’s Department. Deputies searched the waterways between Rio Vista and Isleton in the area near the Three Mile Slough Bridge with assistance from the Rio Vista Fire Department. After a two-hour search, the rescue mission switched to a recovery operation with the three people still missing, according to a Facebook post. The Coast Guard is assisting in the investigation. Officials did not release information about those involved or how they ended up in the water. Sam Whiting is a staff writer for the San Francisco Chronicle. Email: [email protected] Sam Whiting has been a staff writer at The San Francisco Chronicle since 1988. He started as a feature writer in the People section, anchored by Herb Caen’s column, and has been writing about people ever since. He is a general assignment reporter with an emphasis on feature writing. He lives in San Francisco and walks three miles a day on the city’s steep streets.