The adult victims appeared to have died sometime yesterday in the city of Tucson, the Arizona Daily Star said.
Tucson police were not immediately available to comment.
The victims found in the single-storey home were men and women, the paper said, quoting Tucson Police Chief Roberto Villasenor.
Police initially called the incident a murder-suicide but Villasenor later said it was too early to confirm this, the newspaper added.
The police chief said they were alerted by a man who went to the house to meet an acquaintance, looked inside and saw someone with clear signs of trauma.
Police would not comment on whether weapons were found inside.
