An Amber Alert was issued Monday evening by Shaunavon RCMP for seven-year-old Luna Potts and eight-year-old Hunter Potts.
Both Luna and Hunter Potts are believed to be with 50-year-old Benjamin Martin Moore of Eastend, Sask.
Moore is described as five feet 10 inches tall, weighing 200 lbs, with black hair.
They may be travelling in a 2015 dark blue Chevy Equinox, Alberta license plate CGC2492.
The mother of the children, 45-year-old Leah Potts, is believed to be travelling with them.
The alert noted that they may have entered the United States.
The public is instructed that if you see Luna, Hunter, or Leah Potts or Benjamin Martin Moore or have information regarding their whereabouts, call 911 immediately or 1-877-SOAMBER (762-6237).
Updates will be issued on the Sask. Alert website: saskalert.ca.