Tung Chung residents are worried that some people living at Caribbean Coast did not go into quarantine after they saw a flat or two still had lights on.
Last week a 39-year-old domestic worker from the Philippines was confirmed to have the virus- she carried the N501Y and E494K mutations, first found in South Africa and Brazil. A 10-month-old baby living with the woman also tested positive.
About 400 households - around 1,020 residents - in block 11 of Caribbean Coast were sent into 21-day quarantine at Penny's Bay Quarantine Centre, Lei Yue Mun Park and Holiday Village, Silka Hotel in Tsuen Wan and Dorsett Hotel in Kwun Tong on Thursday.
However, 10 households have yet to be sent into quarantine. The Department of Health said the contact tracing office is following up.
The authorities said on Friday that 950 residents from the block tested negative for the virus.