CHICAGO (CBS) — Mark Vallas, the son of former Chicago Public Schools CEO Paul Vallas, died on Saturday at a substance abuse center in Huntington Beach, California.

Paul Vallas’ brother, Dean Vallas, confirmed Mark died Saturday afternoon.

Mark Vallas (Photo supplied to CBS)

According to the Orange County Coroner’s office, Mark Vallas, 24, died at New Existence Recovery, a substance abuse treatment facility in Huntington Beach. The coroner’s office said the cause of death was under investigation. An autopsy was scheduled for Monday.

Dean Vallas said his nephew’s death was a “complete shock to the family.”

Mark Vallas’ father, Paul Vallas, was the chief executive officer of the Chicago Public Schools from 1995 until 2001. He ran for governor as a Democrat in 2002, but narrowly lost the primary election to Rod Blagojevich. He later ran school districts in Philadelphia, Louisiana, and Bridgeport, Conn. He also worked on a school reconstruction project in Haiti after the 2010 earthquake. In 2014, he was Pat Quinn’s running mate in Quinn’s failed bid for re-election. Most recently, Paul Vallas has served as chief administrative officer at Chicago State University, but he resigned in January while weighing a potential bid for mayor in 2019.