World War II bomb
An Air Force bomb squad detonated a photoflash bomb from World War II that was washed ashore on St. Pete Beach, Florida, Sunday. In this photo, dated May 27, 2015, a disarmed World War II bomb is pictured on the platform of a truck near Muehlheim Bridge in Cologne, Germany. Getty Images/AFP/Rolf Vennenbernd

An Air Force bomb squad detonated a barnacle-covered explosive from World War II that had washed ashore on the beach in St. Pete, Florida. The 4-foot cylindrical bomb was spotted by a beachgoer who alerted officials Sunday morning, according to reports.

Sgt. Ali Rose of MacDill Air Force Base confirmed the military ordnance to be a M122 photoflash bomb. According to USA Today, officials said the bomb "appeared to have been submerged for a significant period."

Authorities of the Pinellas County Sheriff's Office, Florida, and MacDill Air Force Base, reportedly evacuated about 250 beachgoers and about 25 homes before blowing up the bomb. They built a 900-foot safety boundary around the explosive device and further expanded it to about 1,400 feet before safely detonating it around 5 p.m., the Associated Press reported.

According to the Massachusetts Institute of Technology, photoflash bombs were dropped by military aircraft and detonated in the air to produce light for photographs, according to a description on MIT’s website. The advent of satellite imagery and better nighttime optics eventually made photoflash bombs obsolete.

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