Supermarkets stocked up as long lines formed. The Chinese authorities ordered mass testing to contain a rising number of cases in an affluent district of the capital.

By Keith Bradsher & Chris Buckley @ NYTimes.com, April 25, WITH VIDEO & PHOTOS

BEIJING — Families in Beijing rushed to stock up on food. Supermarkets stayed open late. Residents endured long lines for mandatory testing. China’s stock markets plunged.

A fresh coronavirus outbreak in China’s capital has raised concerns that Beijing could become, after Shanghai, the next Chinese megacity to put life on hold to contain the spread of the Omicron variant. The central government has leaned heavily on lockdowns despite their high social and economic costs, in pursuit of the Communist Party leader Xi Jinping’s “zero Covid” strategy of eliminating infections.

On Monday, the Beijing government said that 70 coronavirus cases had been found in Beijing since Friday. Nearly two-thirds have been in the district of Chaoyang, which ordered all 3.5 million residents to take three P.C.R. tests over the next five days. In other cities, mass testing in response to initial coronavirus cases has sometimes been a prelude to stringent lockdowns, like the four-week one in Shanghai that has kindled widespread complaints from residents there [....]

“Chaoyang District is now the topmost focus for pandemic prevention,” Cai Qi, the Communist Party secretary of Beijing, and a protégé of Mr. Xi’s, said in instructions cited in the official Beijing Daily newspaper on Sunday. Mr. Cai appeared determined to show that Beijing would not be hesitant about taking steps to stifle infections, which has been a criticism leveled by some at Shanghai [.....]