An armed robber fired a shot from a handgun as he held up a dairy in the Wellington surburb of Kilbirnie - but that didn't stop the plucky female shop assistant taking to him with a broom.

The lone robber pointed the gun at the female shop assistant behind the counter of the Devyish Superette on Kilbirnie Crescent, this afternoon.

He demanded money and fired a shot at the ceiling - before running off with the cash.

But as he was leaving, the woman hit him on the head with a broom handle.

Police say the offender may have an injury to his head that requires medical attention/

The offender is described as a male Caucasian, aged in his mid-twenties.

Police say they're providing support and welfare to the store assistant.