St. Louis police say a man upset with his ex-girlfriend shot her and her mother to death then set a fire before leaving two young children locked in an apartment. The suspect's 10-month-old son died of smoke inhalation and a 3-year-old girl was critically injured. Prosecutors charged 23-year-old Eric Lawson on Sunday with three counts of first-degree murder and nine other charges, including arson. Police say 22-year-old Breiana Ray and her mother, 50-year-old Gwendolyn Ray, died Saturday of gunshot wounds to the head. Aiden Lawson died of smoke inhalation. The 3-year-old girl was taken to a hospital suffering from smoke inhalation. Her name was not released.