The three children in eastern Germany used powerful magnets to remove the rusted shells and bullets from World War II from the pond without hurting themselves.
They called the police when they were found near the town of Ohrdruf.
The police blocked the area and urged the public to immediately report any such findings and leave ammunition alone. It is not clear why the ammunition was dumped in the pond.
Germany was littered with explosives after the war because of the intensive air raids by British, US and Soviet bombers.
Bomb disposal experts must deal with these findings because the old detonators can detonate themselves. These findings are usually made on construction sites.