Firefighters are responding to a battery fire at Rocket Lab's Mangere premises near its "mission control" office.
Three fire appliances and three ambulances are attending the scene on Airpark Drive near Auckland Airport, a Fire and Emergency New Zealand spokeswoman said.
Firefighters wearing breathing apparatus could be seen entering the building.
One person could be seen being checked by St John staff in the back of an ambulance.
A witness said there was no visible smoke coming from the business.
Rocket Lab communications manager Morgan Bailey said Fire and Emergency attended a callout at the company's premises due to smoke releasing from a battery.
"No one was injured in the incident."
She said firefighters are "remaining on site as a precaution while the battery returns to a normal temperature".
The incident was near Rocket Lab's "mission control" office, which is the company's base of operations in Auckland, Newshub reported.
The Electron rockets assembled at Rocket Lab make extensive use of batteries.
Unlike traditional propulsion cycles based on complex and gas generators, the Rutherford engine adopts an entirely new electric propulsion cycle, making use of high-performance DC electric motors and lithium polymer batteries to drive its turbopumps.
The emergency incident follows the rocket company's successful launch on January 22 of its second rocket "Still Testing".
It was launched from Mahia Peninsula, successfully reaching orbit before deploying a customer payload eight-and-a-half minutes later.
Chief executive Peter Beck said at the time that the day marked a new era in commercial access to space.
"We're thrilled to reach this milestone so quickly after our first test launch," he said.
The company plans a third test launch - into a Sun-synchronous orbit of between 300km and 500km above the Earth's surface - before it can move into commercial missions.