A robber with a large knife struck twice in Nelson suburb on Thursday night.
A dairy owner in Tahunanui was confronted about 7pm, but the offender left empty handed when the owner escaped to the back of the shop and called for help.
Ten minutes later, police say the same offender threatened a lone attendant at a Mobil service station shop and was given a small amount of money.
Police later arrested a man in the city.
A man, 33, has been charged with aggravated robbery.