The shooting occurred just around 7:30 p.m. Saturday.
Paramedics tell Nexstar’s WGN that a teenage boy was shot in the chest and hurried to Ann & Robert H. Lurie Children’s Hospital of Chicago in critical condition. He was later pronounced dead.
The boy has not yet been identified.
Police have taken two persons of interest into custody and recovered two weapons at the scene.
After the shooting, a WGN News camera crew witnessed officers clearing the area, dispersing the crowd to neighboring streets.
Hundreds of people were at the park Saturday as part of demonstrations across the U.S. protesting a recently leaked draft opinion that suggests the Supreme Court is prepared to overturn the constitutional right to abortion. It is unclear if the teen who was shot was part of the demonstrations.
Millennium Park will remain closed through Sunday.
The Associated Press contributed to this report.