The Brief Rockdale County High School and Heritage High School were placed on lockdown following separate bomb threats. Conyers police and the Rockdale County Sheriff's Office are investigating and working to identify who is responsible. Two Rockdale County high schools were placed on lockdown Tuesday as authorities investigated separate bomb threats. What we know:The Conyers Police Department and Rockdale County Sheriff's Office responded to threats involving Rockdale County High School and Heritage High School. The Rockdale County Sheriff's Office said it was actively investigating a safety threat made toward a local school and was working with Conyers police to identify the person responsible.