The new cases are tied to a wholesale market.

Beijing is preparing for a possible second wave of coronavirus infections as it races to contain a fast-moving cluster centered around a large wholesale food distribution market in the southern part of the Chinese capital.

Beijing has some of the strictest preventative measures in China since the virus was first detected in the city of Wuhan, some 700 miles away. Beijing has largely avoid a sustained outbreak, with zero local cases of COVID-19 for over 50 days.

But 79 new confirmed cases have been linked to the enormous 260-acre Xinfadi wholesale market, which touts itself as the largest agricultural market in Asia, serving the capital as well the bordering provinces of Hebei, Liaoning, Shandong and Shanxi, since last Thursday.

Gao Xiaojun, a spokesman for Beijing’s municipal health commission, said Monday that the city has already tested total of 76,499 people, with an additional 59 positive cases.

Chinese Politiburo member, Sun Chunlan, who has been responsible for China’s coronavirus response, warned Sunday that “the market is densely populated and highly mobile and the risk of the epidemic spreading is high.”

He added, “It is necessary to take firm and decisive measures to effectively prevent the spread of the epidemic.”

According to the Worker’s Daily newspaper, the general manager of the market as well two local officials have been removed from their jobs for negligence.

On Saturday, the Fengtai district government, where the market is located, said it adopted “wartime mechanisms” by closing the market. The concern now is the how far this cluster has spread. New cases have been detected in Liaoning, two provinces away from Beijing.

The source of the new outbreak is unclear. China’s Global Times reported that supermarkets and restaurants across Beijing have been taking salmon off their shelves after the virus was detected on the cutting board of an imported salmon vendor.

China’s top three salmon importers are Chile, Norway and the Faroe Islands.

In an interview with CCTV Sunday, China CDC researcher Yang Peng said the low temperatures within the market itself may have aided transmission and that preliminary tests of the virus showed it is was similar to the strain found in Europe. He said he was unsure how the virus was introduced into the market.