When a masked man came to the counter demanding money the dairy worker thought it was a joke.

Moments later he was hiding behind a door in the back of the dairy after being threatened with a knife.

The Discount Dairy Woolston, on Ferry Rd, was robbed about 8pm on Saturday.

SUPPLIED A masked man demands money from a dairy worker.

Employee Meghamesh Patel said his colleague thought the man, who was wearing a halloween mask, was "playing around" at first.

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"But after a couple of seconds he showed the knife and realised it was a robbery."

CCTV footage shows the employee run to a room at the back of the dairy, while the robber empties the till and runs off with about $800.

The robbery is the latest in a spate to hit the area in recent months. The Night 'n Day, which is less than 200m up the road, has been robbed eight times since August.

Patel said working at night was "scary".

"I don't know what's going on in Woolston. It's happening more and more often."

Staff had placed a baseball bat under the counter in response to the robberies.

"The manager told the employees if something goes wrong don't try and fight them, just let them go.

"We've still got the baseball bat there but we don't have time. We panic when they come with a weapon, we don't want to fight them."

Patel said the staff member was uninjured in the robbery.

"He's good, that's the big thing. We don't care about money."