GRAND RIDGE, Ill. (CBS) – Two children found inside a burned home in downstate Grand Ridge on Thursday were stabbed to death, and the adult found with them committed suicide, say LaSalle County authorities who attribute the fire to arson.

Autopsies found that Jordan M. Shepard, 11, and Jake R. Shepard, 9, sustained stab and cutting wounds, a news release issued Friday said. Jennifer L. Shepard, 36, died from similar wounds.

The sheriff’s office says an occupant of the home returned from work Thursday afternoon to find the house engulfed in flames. Firefighters who responded discovered all of the victims dead in an upstairs bedroom.

A weapon was recovered at the scene, LaSalle County authorities said.

Grand Ridge is near Ottawa.

The investigation continues.

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