The gunman who stalked and then fatally shot a grandmother and her 1-year-old grandson inside a Florida supermarket had been threatening to kill people, including children, on his Facebook page but no one reported him, a Florida sheriff said.

Timothy J. Wall, 55, had been making the threats for some time before he walked into a Publix in Royal Palm Beach on Thursday, stalked his victims in the produce aisle before first shooting the child and then the woman before killing himself, Palm Beach County Sheriff Ric Bradshaw and his detectives said. Detectives have found no connection between Wall and the woman.