At least 20 people were injured, one fatally, when gunfire erupted early Sunday at a Juneteenth celebration in suburban Chicago, authorities said.

The shooting unfolded about 12:30 a.m. in the parking lot of a strip mall in Willowbrook, about 23 miles west of Chicago, according to the DuPage County Sheriff's Office.

The gunfire erupted during a large gathering to commemorate Juneteenth, Battalion Chief Joe Ostrander with the Tri-State Fire Protection District told ABC Chicago station WLS-TV.

Victims were taken to multiple area hospital with gunshot wounds, according to the sheriff's office. One person was pronounced dead and at least two were in critical condition, Deputy Chief Eric Swanson of the DuPage County Sheriff's Office said at a news conference.

No arrests have been announced.

A motive for the shooting is under investigation.

Witnesses described a scene of panic with people scattering in all directions, seeking cover from the barrage of gunfire.

"It was supposed to be like a Juneteenth celebration; we just started hearing shooting, so we dropped down until they stopped. They just kept going. After that, we literally scattered away," witness Markeshia Avery told WLS-TV.