Sergeant Jeff Kinder says the 36-year-old suspect was found dead early today from an apparent self-inflicted gunshot wound.
Investigators say the attacks took place in multiple locations in and around the town of Tyrone, about 65 kilometers north of the Arkansas border.
Authorities have not named the victims or the gunman. The victims were found at four different homes.
One injured person was taken to a hospital. An investigation is ongoing. A motive for the killings and possible connections between the shooter and victims were not immediately clear.