In a departure from the norm in such cases, guns were apparently not used in the killings.
"There were two beaten with a blunt object and seven hanged," Roberto Ramirez, Nuevo Leon state prosecutor, said in this fairly well-off industrial city close to the US border.
The victims, all men, had their hands bound with thick tape, he said. Their bodies were being examined by the forensics unit.
Some narcotics residue and drug paraphernalia were found at the home, located in an upscale residential area, the prosecutor said.
Gangsters in the area operate with a sense of impunity, and it's not uncommon for them to carry out killings openly.