fireworks2ST. LOUIS (AP) — With vague threats of terror attacks in America over the Fourth of July weekend, extra precautions are being taken during Fair St. Louis.

Police are patrolling a chain link perimeter fence with metal detector checkpoints at the festival in Forest Park. Plain-clothes officers in the crowd are watching for anything unusual.

The fair is one of the nation’s largest Independence Day events. It is being held in Forest Park for the second straight year while reconstruction of the Gateway Arch grounds continues.

Police Chief Sam Dotson says the precautions follow concerns about individuals radicalized by propaganda from terror groups.