ATTICA TOWNSHIP, Mich. (AP) _ Five people, including three children, were found dead Wednesday in their rural home, and authorities suspect they were overcome by carbon monoxide fumes.

Sheriff's Lt. Gary Parks said investigators believe a quarter-inch gap between the home's furnace and its exhaust pipe caused the odorless gas to leak into the house.

Blood tests would be performed to confirm that preliminary finding, Parks said.

The victims were a 31-year-old mother, her 37-year-old boyfriend and her three daughters, ages 6, 8, and 10. Parks said they were discovered by the girls' grandparents, who became concerned after learning the children had not been to school for a few days.

A dead dog also was found in the rural Lapeer County home, about 45 miles north of Detroit. The family's cat was alive, Parks said.