NEW : Police chief 's son also suspected in death of another officer . Dallas , Texas , officer killed in suburban Dallas shootout . Authorities at an afternoon press conference Monday wore black bands around their shields to mark the death of their fellow officer . Chief 's son also slain during exchange of gunfire with responding officers .
NEW : Police chief 's son also suspected in death of another officer . Dallas , Texas , officer killed in suburban Dallas shootout . Chief 's son also slain during exchange of gunfire with responding officers .