Police say a suburban Chicago man shot and killed his wife and two of his children before he died of unknown causes.

Robbins Police Chief Mitchell Davis says 43-year-old Michael Worsham shot his 17-year-old son in the head on Sunday before pulling his wife out of bed and fatally shooting her. He also shot his 15-year-old daughter in the back as she tried to flee, then went outside, shot her again and dragged her back into the house.

A 14-year-old stepson escaped with the boy's 5-year-old nephew.

Davis said Monday that police don't yet have a motive for the slayings. They say Michael Worsham's body had no gunshot wounds and his cause of death was not yet clear.

Authorities say they had no record of domestic violence at the home.