Don’t be alarmed if you see military helicopters flying along Chicago’s lakefront over the next few days, city officials say — its all part of an event taking place in downtown Chicago this weekend, the Chicago Office of Emergency Management and Communications said.

According to an alert from the OMEC, military helicopters will be flying in formation along the lakefront in downtown Chicago over the next few days as practice for “upcoming flyovers that will take place during an event this weekend.”

In the alert, the OEMC added that the public should remain aware of their surroundings, and to report suspicious activity, especially in large gatherings, to law enforcement.

The OMEC did not elaborate on what specific event the helicopters would be part of, although several large events are set to take place in Chicago over the busy Fourth of July weekend, beginning with a fireworks show at Navy Pier Wednesday.

Friday and Saturday, the second annual NASCAR Chicago Street Race is set to take place in and around Grant Park, with two races around a 2.2-mile race course, concerts and more. The race will also see dozens of street and sidewalk closures, including parts of Michigan Avenue and DuSable Lake Shore Drive.

Additionally, two iconic Chicago festivals — the Taste of Chicago and the Chicago Air and Water Show — that typically take place in the summer time has shifted their dates due to the NASCAR street race, and the upcoming Democratic National Convention, which is scheduled to take place at the United Center in August.