Authorities responded at about 9:16 p.m. in the 1300-block of Beach Street.
A man was found with serious injuries after authorities believe a firework mortar struck the man in the face and exploded.
A medical helicopter was requested, but was unavailable due to inclement weather.
The man was transported by ambulance to Northwestern Medicine McHenry Hospital.
The McHenry County Sheriff's Office is investigating the incident.