NHS Western Isles has warned of rising cases of Covid-19 on Barra.
The health board has confirmed 10 positive cases on the island, with two of the people affected receiving hospital treatment.
Chief executive Gordon Jamieson said it was a "rapidly developing situation" and has appealed to people to only leave home if "absolutely essential".
Separately, a single positive test of Covid has been confirmed on Benbecula in the isles.
The warning comes amid a rise in cases on Barra in the past few days.
One person has received treatment at Western Isles Hospital in Stornoway in Lewis, and another in a hospital on the mainland.
Local authority Comhairle nan Eilean Siar has closed Barra's Castlebay Sports Centre and visits to the island's St Brendan's Care Home and Hospital have been suspended as part of efforts to tackle the outbreak.
Mr Jamieson said test and protect procedures were ongoing and a "significant number of additional tests would be done.
He said: "We would appeal to everyone, particularly the residents of Barra, to limit their contact with other households and only to leave home if absolutely essential.
"Please continue to take every precaution you can. We must contain and supress this virus."
Local councillor Donald Manford said there had been "shock and dismay" at the rise in cases.
He said: "We have been many, many months clear of the infection. We reacted immediately to limit circulation and are working tirelessly to protect ourselves."
Level three restrictions apply in the Western Isles, Orkney, Shetland and some islands in Argyll and Bute and the Highlands. These are Coll, Colonsay, Erraid, Gometra, Iona, Islay, Jura, Mull, Oronsay, Tiree, Ulva and all islands in Highland, except Skye.
In-house socialising is not allowed, but people can meet one other household indoors in a public place such as a café or restaurant and outdoors in a private garden or in public area such as a park.