Illinois State Police have issued an Amber Alert for two brothers from the central Illinois city of LeRoy in McLean County.

The McLean County Sheriff's office says 9-year-old Duncan G. Connolly and his 7-year-old brother Jack D. Connolly were last seen at 6 p.m. Sunday. Police say the boys were last seen with their father, Michael Connolly.

Their mother, Amy Leichtenberg, told The (Bloomington) Pantagraph that Connolly was scheduled to drop the boys off at the LeRoy Police Department on Sunday, but never showed up.

LeRoy Police Chief Gordon Beck says he considers the boys' disappearance a criminal investigation.