A woman preparing food at a bakery was threatened by masked men, one wielding a hammer, during a hold-up early today.
Three men smashed into the Mapua Village Bakery about 30km from Nelson at 3.30am.
Detective Senior Sergeant Craig Johnston said one man was armed with a hammer and another threatened to hurt the woman if she didn't hand over cash.
All three robbers had their faces covered.
Two shop tills containing an unknown amount of loose cash were stolen.