Authorities say Luis Prado took 4-year-old Jacqueline and 2-year-old Aleny from the area of 7800 South Laramie in Burbank on Friday. He drove away with them in a red 1994-1995 Acura with tinted windows and a Texas license plate. The license number is unknown.
Police say he may have fled to San Luis Potosi, Mexico.
Anyone with information should contact Chicago police.