Armed police put a currency exchange store in Wellington's CBD into lockdown this morning after it was subject to an aggravated robbery.

Police have charged a man, 43, with aggravated robbery and possession of an imitation firearm.

A man presented his handgun to staff at the Travelex Currency Exchange on Lambton Quay, demanding cash, Detective Senior Sergeant Tim Leitch said.

Leitch described him as tall, thin man, possibly of Māori descent, who was wearing dark clothing, a black baseball cap, a mask and backpack.

"He made off after obtaining an undisclosed amount of foreign currency."

However, Police identified a car in connection to the robbery in Lower Hutt around 3.45 this afternoon.

Armed police stopped the vehicle shortly after on State Highway 58 at the Haywards Interchange.

"The staff members were not injured however [sic] have been shaken by the incident and are being supported. There were no customers in the store at the time," Leitch said.