Tonga will enter a two-day nationwide lockdown from Wednesday night after recording two asymptomatic community cases of COVID-19.
Prime Minister Siaosi Sovaleni announced the two cases had been working at the wharf in the capital Nuku'alofa and were now in isolation.
The Pacific Island nation had previously only reported one case of COVID-19 in October last year.
Outside of that, Tonga had been COVID-free since the start of the pandemic.
The new cases were detected during routine testing at the wharf. It is believed one of the cases might have been positive last week.
Close contacts of those infected are believed to have travelled to Tonga's outer islands, prompting the lockdown of the whole country from 6pm.
Schools will be closed and civil servants will not be required to work.
The Prime Minister has also urged people to wear masks in public.
Sat Narayan, who manages a supermarket in Tonga's capital Nuku'alofa, said there was a sense of unease in the community following the news of the infections.
"Until now we haven't had any issues with the coronavirus … so we're panicking," Mr Narayan said.
He said people were stocking up on food and essential supplies in preparation for the lockdown.
Mr Narayan is waiting for advice from the Tongan government about whether his business will have to close during the lockdown.
'Worst-case scenario' as lockdown hits after eruption
The lockdown comes as Tonga struggles to recover from a volcanic eruption and tsunami last month, which destroyed villages and resorts and severed communications to the island, which has a population of around 105,000 people.
"We're scared because this is not normal for us here in Tonga," Tongan journalist Marian Kupu told the ABC.
Authorities have not confirmed if the cases are linked to the HMAS Adelaide, which arrived in Tonga last week to deliver aid supplies with 23 confirmed COVID cases on board.
The ABC has been told that figure has now risen to as high as 70. Further information has been sought from the Department of Defence.
Authorities have insisted that foreign aid donors deliver supplies without any person-to-person contact to prevent potential transmission.
Officials have confirmed that Australia and New Zealand are fast-tracking booster shots to Tonga, with 10,000 coming immediately from Australia, according to local media reports.
Currently around 85 per cent of Tonga's eligible population have received two doses of the COVID-19 vaccine.
Tonga's main island went into a snap seven-day lockdown in November after the country recorded its first COVID case.
A passenger from New Zealand had tested positive for the virus in hotel quarantine and the lockdown was called despite no community transmission being detected.
