A police spokesperson said emergency services and the NZDF bomb disposal unit from Burnham were called to a Woolston business' car park around 9am after the "suspicious-looking device" was found.
Police closed Ferry Rd from Ensors Rd to Hopkins St while they dealt with the device.
"Someone saw something that looked a bit out of the ordinary, and we are there assessing if there is any risk posed from it," the police spokesperson said.
A witness said he heard a small controlled explosion in The Tool Shed car park on Ferry Rd about 9.30am.
He said a bomb disposal expert in protective equipment was in the car park a few minutes before the loud bang went off.
Multiple shops on Ferry Rd were evacuated following the device's discovery. Police also set up roadblocks and traffic diversions.
"The road will be closed in both directions while police conduct a scene examination," the spokesperson said.
He said the device was left on an empty section at the corner of The Tool Shed.
The shop owner said police showed him a photo of a can, which he said was “similar to a large V can” and had fluid inside.
The can reportedly had wires coming out and an electrical device strapped to the side.
The shop owner told NZME "it’s gutting" the incident had such an impact on the area. He said customers could not come and go from his business as a result.
Staff from The Tool Shed were evacuated. However, they would not comment on the incident at this time.
-By Geoff Sloan and Nathan Morton, NZ Herald
