The Army bomb squad was called to Masterton yesterday to investigate the discovery of a World War I bomb in the attic of a Queen St shop.
Neighbouring shopkeepers were told at noon to vacate their stores and move away from the area while the bomb disposal team dealt with the find, which turned out not to be a live round.
It was identified as an 18-pound shrapnel ordnance.
Police Senior Sergeant Mike Sutton said it was a common type of bomb in WWI: "It's filled with shrapnel. It gets fired, it's set on a timer and then it explodes. One of the businesses was having a bit of a tidy-up and found an old World War I-era bomb, which had been in the family for sometime but that they had forgotten about."