Several explosions heard around North Beach Saturday and Sunday have been confirmed to be the controlled detonations of unspent anti-aircraft explosive rounds used in military exercises dating back decades and found on the beach this past weekend.

The Grays Harbor Sheriff’s Office warned the public to “don’t touch, don’t move, don’t transport” any similar device if found, and deputies have received “multiple reports of military 20 mm anti-aircraft high explosive rounds being located in the North Beach.”

Although no official notice or public warning had been issued prior to the detonation, numerous people reported hearing at least one loud explosion. Reports on the Grays Harbor Scanner Facebook page included a photo of a military bomb truck from Saturday night and another photo of two craters where the devices were said to have been detonated near Copalis Beach.

“They are unspent anti aircraft ordinance. Probably from World War II,” according to one post from those who found one. “They are washing up all over the beaches. With their current condition they are unstable.”

The Navy continues to conduct exercises off the coast, but what was found this weekend likely dates back to the 1940s.

“These rounds are described as being 6-8 inches in length and 20 mm in diameter. They have the resemblance of large rifle ammunition. Many of these rounds have been located encased in a black rock or sludge matter. These rounds should be considered dangerous,” said Grays Harbor Sheriff Chief Criminal Deputy Brad Johansson.

One person on the Grays Harbor Scanner Facebook page noted: “They’re everywhere in front of the old Navy Base (at Pacific Beach). I was walking my dog the other day and couldn’t help but notice them laying everywhere.”

The Sheriff’s Office recommendation: “If located or if you have collected one of these rounds, leave it in place, mark its location, and call Grays Harbor County Dispatch at (360) 533-8765.

“These military rounds are believed to be from the 1940s which makes their stability unknown. These rounds can explode upon impact,” Johansson said.