Naperville police said during a protest on June 1, 2020, someone threw multiple explosive devices, causing minor injuries to several officers.
Christian Rea was charged with civil unrest in the incident. Federal investigators allege Rea threw the device, injuring the officers and causing panic in the crowd.
Rea pleaded guilty Tuesday during a hearing over the phone.
WATCH: Naperville protests: Video shows explosion that injured several police officers
Naperville police release video of explosion that injured officers
Sentencing is set for 10 a.m. March 24, 2022.
On June 1, 2020, a large crowd gathered in Naperville for a peaceful protest in which the police chief knelt in solidarity with demonstrators.
But just after 10 p.m., large crowds were reported near Aurora Avenue and Main Street. According to witnesses, outside groups pulled up and damaged multiple businesses in the downtown. One witness said a restaurant and a jewelry store had its windows smashed.
A SWAT Team was called to a Walgreens downtown after a group of people threw rocks and caused damage to the building, police said.
The video in the player above is from an earlier report.