The large port of Tianjin could face the first local outbreak of the Omicron variant of the coronavirus in China, regardless of its size, less than a month before the opening of the Winter Olympics in neighboring Beijing.

State broadcaster CCTV said the government has divided Tianjin and its 14 million people into three levels of restrictions, starting with the lockdown areas where people are not allowed to leave their homes at all.

In control zones, each household is allowed to send a family member away to do grocery shopping every other day, while in prevention zones, people must stay in their immediate vicinity.

Buses and trains from Tianjin to Beijing have been suspended, and people are urged not to leave the city unless they have urgent business.

The city began mass testing all of its residents on Sunday after a group of 20 children and adults tested positive for Covid-19, at least two of them with the Omicron variant.

Another 20 people tested positive on Sunday, bringing the total to 40. Officials earlier said the virus was circulating, so the number of cases could rise.

China has stepped up its strict zero tolerance strategy ahead of the Olympics, which will open on February 4.

The Chinese capital is 110 kilometers northwest of Tianjin, and many people regularly make the round trip by car or on a high-speed rail link that takes less than an hour.

Elsewhere, millions of people are confined to their homes in Xi’an and Yuzhou, two more distant cities but with larger epidemics due to the Delta variant.

Residents of Xi’an have been in detention for more than two weeks, but the city’s number of new cases from 13 million fell to just 15 on Monday, a sign that restrictions may soon be lifted.

Yuzhou is a city of about 1.1 million people in neighboring Henan Province.

Another 60 cases were reported in Henan on Monday, including two of the Omicron variant, state media The Paper reported.

The provincial capital of Zhengzhou has conducted mass tests and closed its schools. Another 24 cases were reported in the city on Monday.

China had reported a dozen cases of Omicron previously, most among people who arrived from overseas and were isolated.

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