Sr. Cpl. Sherri Jeffrey said Tuesday that the house has no central air conditioning and is cooled by window units and fans.
Jeffrey says the boy was pronounced dead late Monday at a hospital. His mother told police that the child complained of being hot and she tried to cool him by putting him into a tub of cold water.
Jeffrey, who had no information on how hot it was inside the residence, says police did not observe any signs of abuse of the boy. An autopsy has been ordered.
Forecasters say Monday was the 24th straight day of temperatures at 100 degrees or higher in North Texas.