Altoona police say 62-year-old Aaron Wilson Dishong set the fire in an attempt to kill his ex but only two young children and their mother were inside.
Three-year-old Daryl Etchison Jr. was killed in the blaze. Authorities say his mother jumped from a third-floor window to save herself and her 2-year-old daughter.
Dishong allegedly incriminated himself during a phone call with a witness that was monitored by police. Investigators say he had been stalking his ex-girlfriend, who had a restraining order against him.
Dishong was jailed Thursday night on homicide, arson and related charges. He denied setting the fire following his arraignment.
Etchison's mother remains hospitalized.
