Coronavirus cases in a Cornwall town have "sky-rocketed" and are comparable with parts of London.
The seven-day rate in Newquay West on Monday was 878 cases per 100,000 people, and it had been over 1,000 the week before, Cornwall Council said.
Many London boroughs had experienced similar rates, the authority said.
Public health bosses said it was "of huge concern" and people should "take extra care" and "be mindful" of "how easily" Covid spreads.
'Spreading like wildfire'
Recent figures for Hackney and the City of London area showed 871 cases per 100,000 people in the week of 1 to 7 January.
The same period saw 338 cases per 100,000 people for Cornwall and the Isles of Scilly as a whole. The average area in England was 531.
Sally Hawken, council portfolio holder for public health, said coronavirus had been "spreading like wildfire between households in the town".
Case numbers had also been "particularly high" in Truro, Penzance, Bodmin, Falmouth and Saltash in recent weeks, the council said.
Ms Hawken said: "It cannot be understated how serious this situation is, and everyone needs to do everything they can to stop more people being infected and our health services becoming overwhelmed."
Director of Public Health for Cornwall, Rachel Wigglesworth, confirmed the "number of cases in Newquay in particular is of huge concern" and "we are urging people to follow the rules and be mindful of how easily the virus can be spread".