The U.S. Coast Guard has issued a warning to beachgoers and boaters on Lake Michigan after an armed phosphorus flare was found washed up on Montrose Beach on Monday.
According to the Coast Guard, three phosphorus pyrotechnics remain missing following a joint military exercise with the Air Force off the coast of Milwaukee earlier this month.
During the exercise, four phosphorus pyrotechnics failed to ignite after being deployed. On Monday, a lifeguard found one of the devices washed ashore at Montrose Beach.
The Chicago Fire Department’s bomb squad responded and safely disposed of the flare.
This maritime flare, used in a military exercise, washed up on Montrose Beach yesterday. The public is asked to call 911 if they see a similar object. Do NOT touch, move or attempt to handle the item under any circumstances. Contact the U.S. Coast Guard for additional info. pic.twitter.com/Y9uT3WdhzI
— Chicago Police Communications & News Affairs (@CPD_Media) May 27, 2025
The flares are silver-colored cylinders. According to a press release from the Coast Guard sector overseeing Lake Michigan, the undetonated flares are still considered armed. If triggered, they could produce smoke and flames reaching temperatures of up to 2,900 degrees Fahrenheit.
“We urge the public to stay clear of any such item and to immediately call 911,” a Coast Guard spokesperson said.
The Coast Guard did not say if more searches will be done to find the remaining flares.
