Guernsey has gone into lockdown for the first time in seven months after four new cases of coronavirus were discovered among the island's 67,000 population, the island's government has said.
The States of Guernsey said in a statement that it was unclear how the individuals concerned had contracted the disease, as none was from travel or from contacts with known cases.
'Contact tracing is continuing to determine whether there is a link between the cases and whether these cases are linked or if this is a result of wider community seeding,' the statement said.
Tests taken on Friday confirmed the latest cases and efforts to prevent the virus spreading are underway.
The move comes after the island had been free of coronavirus restrictions since early June.
Guernsey has been plunged into another lockdown after the discovery of new coronavirus cases. Pictured: New year day swimmers at Braye Bay, Alderney, Guernsey
In comparison to the Guernsey's four discovered cases, in the UK, as of Monday, the rate of people with at least one positive Covid test was 421.3 per 100,000 population.
Chief Minister Peter Ferbrache, who was appointed to the role in October, said: 'We have four new cases of COVID-19 that have been identified overnight and it is not clear yet if they are linked or how they contracted the virus.
'We must for the moment assume this is the result of community seeding.
'We are announcing these steps with immediate effect in the hope that we can get this quickly under control with a sharp and strict lockdown.
'Unlike before, this is not new to us. We have done this once already, we know as a community that together we can do this successfully and keep each other safe.
'Even in doing this for a second time, we know the rules are not perfect. This isn't about perfection, it's about speed.
He added: 'If we need to update our guidance in the days ahead, we will do so please bear with us. We have taken decisive action. We know a lockdown isn't easy.'
Under the latest measures, islanders have been told to stay home from midday Saturday except for essential shopping, medical care or up to two hours exercise outdoors.
Chief Minister Peter Ferbrache (pictured), who was appointed to the role in October, said: 'We must for the moment assume this is the result of community seeding.'
Non-essential shops and restaurants have been ordered to to close, including for deliveries and takeaways.
Schools will also shut, except for children of key workers, or from vulnerable families.
Dr Nicola Brink, Director of Public Health, said: 'The safety of our community has always been our priority. The reappearance of cases of COVID-19 via unexplained community transmission means that we have to assume that these new cases pose a significant risk.
'A lockdown is the most effective and efficient way to prevent onward transmission of COVID-19.
'We know from other jurisdictions around the world that hard and strict measures introduced quickly generate the best results and that is our focus - to try and get this under control and us back to the normality we have all enjoyed as quickly as possible.'
The first confirmed case of coronavirus on the island was announced on March 9 after a patient returned from Tenerife on their return before a full lockdown was introduced on March 24.
Guernsey's pubs threw open their doors to drinkers for the first time since lockdown in June
But as early as mid April Guernsey - a self-governing British Crown dependency - was on its way out of coronavirus lockdown as gardeners, mechanics, estate agents and builders were given permission to return to work.
Before today, lockdown in Guernsey had been eased from June with residents heading back into pubs and shops.
The island was the first place in the British Isles to reopen pubs after they were forced to close in March last year.
In addition to pubs, hairdressers, gyms, restaurants, cafes, museums and cinemas were allowed to welcome customers again.
In June they had entered phase four of the exit plan from lockdown after Guernsey reported 'no known' Covid-19 cases remained.