A man sitting on a blanket at Festival Park in Elgin during the Fourth of July celebration told police a bullet pierced it, Elgin officials said.
The man was uninjured in the only incident in an otherwise safe weekend in Elgin, officials said in a release.
Elgin officers responded to more than 100 calls from residents reporting fireworks, but nobody was injured. Several citations were given for alcohol-related violations, police said.
Police believe the bullet that went into the ground Friday evening was fired from a long distance outside the park.
"The reckless conduct of shooting a firearm into the air in celebration of an event is not only an illegal practice but also extremely dangerous," officials said in the release.
Elgin police continue to investigate the incident. Anyone with information can call Elgin Police Department's nonemergency line at (847) 289-2700.