A district of Beijing is on a "wartime emergency" footing and tourism has been banned in the Chinese capital after a spike in coronavirus cases centred around a food market has sparked fears of a fresh outbreak.
The move comes amid mounting concern over a second wave of the COVID-19 pandemic.
Eleven neighbourhoods around the wholesale market in the city's southwestern Fengtai district have gone into lockdown, where an official said it was in "wartime emergency mode".
An official has said the area is in 'wartime emergency mode'
The cluster was detected after throat swabs from 45 people, out of 517 tested at the district's Xinfadi market, proved positive for coronavirus, although none of them showed symptoms of COVID-19, according to the authorities.
Officials have said more than 10,000 people at the market will be tested, and the premises disinfected.
A city spokesman said all six COVID-19 patients confirmed in Beijing on Friday had visited the market.
They are the first locally transmitted cases in the city in more than 50 days.
Sky's Asia correspondent Siobhan Robbins said: "People in the area have been told not to leave their houses.
"It is a worrying time for Beijing because it hadn't had a locally transmitted case for almost two months, so it just shows you how tricky COVID-19 is to keep under control, and Beijing isn't taking any chances.
"Not only are these areas in lockdown, some schools and nurseries in the area were closed on Friday, several other markets have been shut as well.
"There is mass testing taking place, officials saying that more than 2,000 wholesale market workers were tested on Friday alone.
"State media are reporting that the chairman of the market said traces of COVID-19 were found on a salmon chopping board - that has led to people getting concerned about food safety standards and an investigation launched across the city," she added.
The virus was first reported at a seafood market in Wuhan, the capital of central China's Hubei province, in December.
There have now been around 7.6 million people infected worldwide and more than 420,000 have died, according to Johns Hopkins University which has been tracking the outbreak.