The lockdown started at 6 p.m. local time Wednesday. Prime Minister Siaosi Sovaleni said there would be no boat or plane travel among Tonga’s roughly 170 islands – three dozen of them inhabited – until further notice. Schools were closed, government workers given time off and masks encouraged in public spaces, according to the Australian Broadcasting Corp.

Sovaleni said the restrictions would be reviewed every 48 hours, local news website Matangi Tonga reported.

It’s not clear how the virus was transmitted into Tonga. Two people who contracted it worked at a port in the capital, Nuku’alofa. There was an outbreak of more than two dozen cases aboard an Australian navy ship, the HMAS Adelaide, that docked at the port last week to deliver disaster relief. Aid also arrived from New Zealand, France, Japan and China -– all countries that have cases.

Sovaleni said Wednesday afternoon that the virus had spread beyond the two port workers to a woman and two children, Radio New Zealand reported.

Curtis Tuihalangingie, a senior Tongan diplomat in Australia, had said the nation’s aim after the volcanic eruption and tsunami was to avoid a “tsunami of COVID” hitting the islands through aid deliveries. The natural disasters Jan. 15 left at least three people dead.

Tonga had previously logged only one coronavirus infection, which was detected in a hotel quarantine in October and triggered a week-long lockdown.

The Tongan government on Wednesday released a list of places where the virus could have spread from the two cases in recent days. They included a church, a kindergarten, a bank and several stores.

Tongan Health Minister Siosaia Piukala said last week that aid supplies from the Adelaide would be offloaded by Australian naval personnel and quarantined for 72 hours before being distributed by Tongan workers. Infected people on the Adelaide were isolating with their close contacts aboard.

The Adelaide has been hampered by a power outage that stranded the ship off Tonga. Most of the ship’s personnel were sleeping above deck due to the heat – there was a high of about 84 degrees Wednesday – according to the ABC.

Australia’s Foreign Ministry did not respond to a request for comment Wednesday. Foreign Minister Marise Payne said last week that Canberra had delivered more than 40 tons of aid to Tonga. It included shelter materials, water and sanitation supplies.

“We appreciate the decision of the government of Tonga to enable HMAS Adelaide to dock and offload the humanitarian and medical supplies,” she said.

Cleanup efforts from the disaster continued. More than 180 people were evacuated from three badly hit islands to Tonga’s most populated island, where they were supplied with tents, kitchen kits and bags of clothing.

About 60 percent of Tonga’s 105,000 residents have been fully vaccinated against the coronavirus.