China’s national oil companies are on high alert and implementing stricter coronavirus prevention rules as cases surge once again in the country’s capital.

During the weekend, Beijing reported 41 new Covid cases, most of which are located in Chaoyang district, where China National Petroleum Corporation (CNPC), Sinopec and China National Offshore Corporation (CNOOC) are headquartered.

A school in Chaoyang reported 10 cases during the weekend. The school, as well as some local communities, has been put under controlled management since Friday, which means residents are barred from leaving the area while they undergo testing.