(CNN) At least three of the seven people killed in Sumner County, Tennessee, were related to the suspect in the slayings, including his mother, father and uncle, Tennessee Bureau of Investigation Director David Rausch said Monday.

The victims also included three generations of another family, a 12-year-old girl among them, and a woman who is not related to Cummins, Rausch told reporters. The victims were likely dead for more than a day upon being discovered, he said.

Michael Cummins, the 25-year-old suspect who has a long criminal record and authorities say was released from prison earlier this year, is hospitalized after being shot by a sheriff's deputy. His injuries are not life-threatening. He has not been formally charged.

An eighth victim, also Cummins' relative, is in the hospital in critical condition, Rausch said.

Authorities discovered six of the bodies and the injured victim off a rural road between Westmoreland and Fairfield, small towns about 50 miles northeast of Nashville. A seventh body was found at a home less than a mile from the primary crime scene, police said.

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