A shooter fired on an Independence Day parade from a rooftop in suburban Chicago, spraying the crowd with gunshots initially mistaken for fireworks before hundreds of panicked revelers of all ages fled in terror. At least six people were killed and at least 30 wounded.

Authorities detained a person of interest in the deadly Fourth of July parade shooting Monday evening in Lake Forest, Illinois.

Police detained 22-year-old Robert E. Crimo as a person of interest in the deadly massacre after a brief pursuit, authorities said. A Chicago police officer spotted Crimo and attempted to perform a traffic stop when the 22-year-old fled, authorities said, according to CNN. Crimo, who goes by the name “Bobby,” was believed to be armed and dangerous at the time he was taken into custody.

A day of national celebration turned to tragedy Monday when a gunman killed six people and injured dozens more at a July Fourth parade in Highland Park, Illinois -- leaving the nation grieving yet another mass shooting.

The suspected shooter, identified by authorities as Robert E. Crimo III, used a "high-powered rifle" in an attack that appeared to be "random" and "intentional," police said. They believe the shooter, who was apprehended later Monday, climbed onto a rooftop of a business and opened fire on the parade about 20 minutes after it started.