Heidi Martinez-Trejo and Carlos Gomez were last seen Sunday afternoon in the 9700 block of Webb Chapel Road in northwest Dallas.
On Tuesday night their family received a note suggesting the two could be in immediate danger, police said.
Martinez-Trejo is described as a 28-year-old Latin woman who is about 5 feet 6 inches tall and 130 pounds. She has black hair with blonde highlights. She was wearing a pink shirt, black hoody and blue pants.
Her young son weighs about 30 pounds and has black hair. He was wearing a green shirt with a white collar.
Police are asking for tips on their whereabouts. Anyone with information should call 911 or the Dallas Police Department's Missing Person's Unit at 214-671-4268.
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