Jerry William Jones was in serious condition Thursday night, but the three girls were safe following a car wreck on Interstate 75 at the Georgia-Tennessee state line, Georgia Bureau of Investigation spokesman John Bankhead told CNN.
Jones apparently shot himself after he crashed while trying to exit the highway, Bankhead said.
Jones was charged with the late Wednesday slayings of the parents and sister of his estranged common-law wife and his 10-month-old daughter, police said.
Gordon County Sheriff Jerry Davis said Jones called his wife and told her of the killings, then threatened to kill his 3-year-old and 4-year-old daughters and his wife's 10-year-old daughter from a previous marriage. A national alert had been put out for his arrest.
A source close to the family told CNN Jones had threatened relatives repeatedly in the past.