New Zealand’s government on Friday extended a lockdown of its largest city Auckland for another 12 days as it tries to stamp out its first domestic coronavirus outbreak in more than three months.

The outbreak has grown to 30 people and extended beyond Auckland for the first time. Until the cluster was discovered Tuesday, New Zealand had gone 102 days without infections spreading in the community. The only known cases were travelers quarantined after arriving from abroad.

Health authorities believe the virus must have been reintroduced from overseas, but genome testing hasn’t found a link with any of the quarantined travelers. That has prompted authorities to investigate whether shipping workers were a source, after several employees at a food storage facility were infected.

Prime Minister Jacinda Ardern said extending the Auckland lockdown, which began Wednesday, would give authorities time to get a handle on the virus cluster and isolate those infected.

“Together, we have got rid of COVID before,” Ardern said in a highly anticipated address. “We have kept it out for 102 days, longer than any other country. We have been world-leading in our COVID response, with the result that many lives were saved and our economy was getting going faster than almost anywhere else. We can do all of that again.”

All of the new cases in the outbreak appear to be linked through family or work connections. The only known infections outside Auckland are two people in the central North Island town of Tokoroa who were visited by infected family members from Auckland. Officials said they thought the chances were low the virus would spread further in Tokoroa.

Several of those infected work at an Americold food storage facility in the Auckland suburb of Mt. Wellington. Officials are looking at the possibility that workers on a freight ship or at the port may have spread the infections, despite physical distancing requirements at those sites and orders preventing ship workers coming ashore.

Director-General of Health Ashley Bloomfield said they were doing rigorous testing at Auckland’s port “as part of our investigation just to follow that chain of the Americold goods that might have come in through the port and been transported to that Mt. Wellington depot.”

Officials are also investigating the possibility the virus could have survived from abroad on chilled or frozen food boxes and then infected workers in New Zealand, a scenario they consider unlikely.-AP

New Zealanders drive to a virus test centre in Auckland, Thursday, August 13.

New Zealand lengthens Auckland lockdown, outbreak involves 30 virus patients