Dickson County sheriff's deputies have charged two teenagers with fatally shooting their foster mother and her mother-in-law.

Nashville television station WSMV is reporting that Mary Clark's foster children, ages 15 and 16, have been charged with two counts of first degree murder in the slayings.

Sheriff's Detective John Patterson said 38-year-old Mary Clark and 66-year-old Gail Clark, who was visiting from Orange, Mass., were found shot to death in separate rooms of Mary Clark's White Bluff home on Tuesday morning.

There was no sign of forced entry or sign of a struggle and one of the women may have been shot while she slept. The slayings probably occurred around 1:00 or 2:00 a.m. but were not reported until about 4:30 a.m.

Officials said they believe there was a motive in the slayings, but have not said what it was.

Mary Clark shares the home with her husband and daughter, but they were out of town on Monday night.

White Bluff, with a population of about 2,500, is about 25 miles west of Nashville.