Zero-covid locks down Chengdu, China's megacity of 21 million

Chengdu has reported more than 900 local transmissions of Covid-19 since August 25. To curb transmission of the virus, Chinese authorities decided to lock down the city of over 21 million people since Thursday, ordering all residents not to leave home unless necessary. Other major Chinese cities have stepped up anti-pandemic measures this week. In the southern technology hub of Shenzhen, authorities shut down Huaqiangbei, the world's largest electronics market. In the northern port city of Dalian, a lockdown was imposed on Thursday and set to run until Sunday in its main urban areas, affecting about 3 million residents. CNN's Kristie Lu Stout reports.