China has placed the capital of Hebei province—Shijiazhuang, a city of 11 million—under lockdown as the city enters “wartime mode” to combat a fresh outbreak of COVID-19 that has infected over 300 people.

On Saturday, China recorded 69 new cases of the coronavirus, double the total of the day before. The majority of new cases were in Hebei, which has accumulated 360 new cases over the last eight days.

The surge is the largest spike since a cluster of roughly 300 emerged in Xinjiang late last year and comes almost a year after Wuhan, the site of the original outbreak, was forced into lockdown. But for China’s political leaders in Beijing, the threat from the outbreak in Hebei literally hits closer to home.

Hebei surrounds Beijing, and the central government is gearing up to host China’s annual gathering of parliament in the capital city in March. Last year’s meeting was postponed for months because of COVID-19.

With the enemy at the gates, China Premier Li Keqiang has effectively called on leaders in Shijiazhuang to not repeat the mistakes made in Wuhan, where officials covered up the extent of the initial outbreak for weeks.

“In the process of prevention and control of the infectious disease, one of the keys is to seek the truth from facts, openly and transparently release epidemic information, and never allow concealing or underreporting,” Li said during a Friday meeting of China’s top administrator, the State Council.

According to local media, Hebei’s leaders have committed to defending the capital, pledging the province will act as a “political moat” around Beijing, protecting it from the viral spread.

On Sunday, Hebei said 13 million people across Shijiazhuang and nearby Xingtai had been tested for the coronavirus since the wave began last week. Officials have suspended public transport in the two cities, while local governments have prohibited travel across city lines and restricted residents to their home communities.

Even with defenses in place, Beijing is already tackling its own outbreak in the capital’s Shunyi district, site of the international airport. Some 30 people have contracted the coronavirus in Shunyi since late December, including a taxi driver. In response, the district has suspended ride-hailing services in the area, except those serving the airport.

Authorities are trying to uncover the source of the new outbreaks. Beijing’s Shunyi cluster has been traced to an arrival from Indonesia, who flew into Fujian province in November before traveling to Beijing after completing a 14-day quarantine and testing negative for COVID-19. Now Beijing requires inbound arrivals to quarantine for three weeks, rather than two.

The source of the Hebei outbreak remains a mystery. Before the sudden outbreak started in early January, the province had reported zero cases since June.