The U.S. Coast Guard is warning boaters and beachgoers on Lake Michigan there are threeundetonated flares in the water that have a risk of exploding. The phosphorous pyrotechnics encased in a silver cylinder are still considered armed, according to a press release from Coast Guard sector overseeing Lake Michigan. If the flare detonates, the smoke and flames could reach a temperature up to 2,900 degrees Fahrenheit. The flares were used as part of a joint exercise between the Coast Guard and the U.S. Air Force in Milwaukee in early May, the release said. During the exercise, four flares were released in the water but did not activate. At the time, none could be located. One of the flares was found May 26 by a lifeguard on Montrose Beach in Chicago, just northwest of Wrigley Field. Coast Guard officials are asking anyone who finds another one to stay clear of it, and immediately call 911. This article originally appeared on Milwaukee Journal Sentinel:Coast Guard warns undetonated flares in Lake Michigan could explode