A husband and wife from Florida were killed when their single-engine plane crashed in a wooded area of central Connecticut, police said Tuesday. The couple crashed late Monday on a ridge along Onion Mountain in Canton. Federal officials are investigating the cause. The victims, Donald Derocher, 73, and Josephine Derocher, 74, lived in Live Oak, Fla., and they were flying to Connecticut to see family, said Police Chief Christopher Arciero of Canton. The 1965 Piper Cherokee aircraft was registered to Donald Derocher. Arciero said Federal Aviation Administration investigators were on the scene.