The U.S. Coast Guard is advising those visiting beaches to avoid any silver-colored cylinders they may find on the shore, warning that they could be armed flares.

According to Coast Guard Sector Lake Michigan, three phosphorus pyrotechnic flares have gone missing following a joint exercise conducted by the Coast Guard and Air Force earlier this month off the coast of Milwaukee.

Coast Guard Sector Lake Michigan issued a warning for three missing phosphorus pyrotechnic flares. (Ninth Coast Guard District)

However, three phosphorus pyrotechnics are still unaccounted for.

The missing pyrotechnics are still considered armed when they do not activate.

Phosphorus pyrotechnics produce a red smoke and flame that can reach temperatures of 2,900 degrees Fahrenheit, according to military officials.