BEIJING (AP) — China’s capital Beijing began testing millions of residents and shutting down residential and business districts Monday amid a new outbreak of COVID-19.

While only just more than 40 cases have been found in the city of more than 21 million since the outbreak surfaced Friday, authorities have implemented extreme measures to prevent a further spread of the virus.

Residents were staying home and stocking up on food as a safeguard against the possibility that they could be confined indoors, as has happened in multiple cities including the financial hub of Shanghai.

The central city Anyang, along with Dandong on the border with North Korea, also announced lockdowns as the omicron variant spreads across the vast country.

China's borders remain largely closed as its hardline response and the pandemic's economic impact continue to grow.