A huge cache of undetonated World War II ammunition and explosives was found near a public beach in northern Poland and is being destroyed, an official said Wednesday.

The explosives came to light when a mushroom picker stumbled across a machine gun belt sticking out of the ground in a pine forest near the Baltic Sea village of Swibno, said Piotr Bik, the official in charge of removing the material.

The stockpile included about 155,000 pounds of undetonated explosives buried by German troops, and 20,000 pieces of other explosive material, including detonators and ammunition, Bik said.

The explosives, if detonated, would have rivaled the force of a quarter-ton bomb, he said, and the detonators were also extremely dangerous as they were only 230 feet from a public beach.

Each one “is dangerous enough to rip off an arm,” he said.

Combat engineers destroyed most of the material Tuesday, and were completing the job Wednesday.

Unexploded bombs from World War II are a relatively common find in Poland and Germany, even more than 60 years after the conflict’s end.