Delivery workers hand packages to residents through the gate of a community area as undelivered packages remain piled up at the gate in Chaoyang district of Beijing March 1, 2020. [Photo by Zou Hong/chinadaily.com.cn]

About 827,000 people who came back to Beijing from outside the city are still in a 14-day quarantine to see if they had been infected with the novel coronavirus, an official said on Friday.

"There's still risk of an outbreak of the disease with people coming to Beijing from other cities and countries," Zhang Tongjun, deputy head of a group for prevention and control work in the city's residential communities, said during an afternoon conference.

Zhang said citizens should not let down their guard about the virus and try to avoid gathering to protect themselves from cross-infection. He added that services for those people in quarantine will be strengthened.

Nearly a million people have participated in the prevention and control of the virus at Beijing's residential communities, including community management employees, public servants dispatched to work at the communities and police who crack down on related illegal activity.

More than 840,000 facial masks, 27,000 temperature detectors and 4,350 protective supplies have been allocated to support their efforts.