Beijing says it is facing its most severe Covid test yet after it saw the country's first coronavirus deaths in six months and cases continue to soar.
Three deaths have been reported in the Chinese capital since Saturday, bringing the country's official death toll to 5229.
The latest fatalities have plunged parts of the city home to more than 21 million back into lockdown.
The deaths come amid rare protests over China's zero-Covid policy.
The controversial strategy - which aims to eradicate outbreaks - has seen seen millions locked down and citizens who have tested positive for the virus forcibly quarantined.
In Beijing, officials have already implemented a lockdown in the Haidian and Chaoyang districts, with shops, schools and restaurants closed.
Those travelling to the capital will also have to do tests for the first three days of their visit, and stay inside until they are given the all-clear.
Millions of other people across the vast country are also under Covid lockdowns, as cases continue to soar despite the efforts of authorities. On Sunday, 24,730 new cases were recorded, nearing the country's daily infection peak in April.
Beijing reported 316 new Covid cases to 3pm Monday local time, according to Reuters news agency. Amongst the three deaths reported since Sunday afternoon was an 87-year-old man.
Liu Xiaofeng - the deputy director of Beijing's municipal Centre for Disease Control and Prevention - described the situation as the most complex and severe yet seen in the city, the news agency added.
A day earlier, a municipality spokesman warned Beijing was facing "a grim and complicated epidemic prevention and control situation", according to China Daily.
While China says its strict zero-Covid policy means that it has seen far fewer coronavirus deaths than much of the rest of the world - although it is thought the true figure could be far higher - there have been repeated stories of delayed emergency treatment for seriously ill people in locked-down areas or quarantine facilities.
In recent days there has been a swell of outrage online, following reports a baby had died because her medical care had been delayed by Covid restrictions.
Earlier this month there were angry demonstrations in the western city of Lanzhou after a father said delays in getting his toddler son to hospital had contributed to his death from carbon monoxide poisoning. Then in October, there were reports of a a 14-year-old girl dying in Henan Province after falling ill in a Covid quarantine centre.
Elsewhere, Hong Kong leader John Lee has tested positive for Covid, the day after he met Chinese President Xi Jinping at a summit in Thailand.