Workers clearing a small garden in northern Germany got a shock when they unearthed a rusted can labeled "Zyklon B" — the deadly poison gas used by the Nazis in the death chambers of Auschwitz and other camps.

Oliver Pohl, a spokesman for police in Kiel, said Wednesday the 150ml-200ml (5oz-7oz) can was unearthed during work Tuesday in the nearby town of Preetz.

Emergency crews determined the can was empty, but still sealed and removed it as a precaution.

Pohl says even though Zyklon B achieved its notoriety through its use in the Holocaust, it was developed in the 1920s as a pesticide. It is known to have been used long ago as a pesticide in the Preetz garden and the can likely pre-dates the Nazi era.