Carl Smith, 12, and his 11-year-old sister Colleen Rahman-Smith were last seen leaving their home on 195th Street near 120th Street Avenue at noon, according to authorities.
An NYPD spokesman could not say where the missing children were heading or why they were not at school Monday, which was not a holiday.
The NYPD released photos of the missing kids.
Smith is approximately 5 feet 7 inches tall with a dark complexion, a slim build, brown eyes and black hair. He was last seen wearing a black T-shirt and blue sweatpants.
Rahman-Smith is approximately 5 feet 4 inches tall and 120 pounds, with a dark complexion, a medium build with black braided hair. She was last seen wearing a tie-dyed T-shirt.
Anyone with information on the missing children are asked to call the NYPD’s Crime Stoppers Hotline at 800-577-TIPS.