Former NFL star Phillip Adams killed himself after shooting dead five people including a prominent doctor, his wife, and their two grandchildren, police say.
Police have not yet established a motive for the mass shooting in South Carolina on Wednesday.
"There's nothing right now that makes sense to any of us," York County Sheriff Kevil Tolson told a news briefing.
Dr Robert Lesslie, 70, and his wife, Barbara, 69, were pronounced dead at the scene along with their grandchildren, Adah Lesslie, nine, and Noah Lesslie, five, the York County coroner's office said.
James Lewis, 38, from Gaston, was working at the property and was found shot to death outside, while an unidentified sixth person was taken to hospital with "serious gunshot wounds".
Adams played for six sides including the San Francisco 49ers and New England Patriots between 2010 and 2015.