Not yet having completely recovered from record-breaking torrential rains last week, Zhengzhou, capital of central China's Henan Province, is facing the challenge of a COVID-19 outbreak.

The city has reported 12 confirmed locally transmitted COVID-19 cases and 20 asymptomatic cases as of 11 p.m. Saturday. A citywide nucleic acid testing was launched on Sunday.

Party Secretary of Zhengzhou's Shangdu Road CPC Community Branch Zhang Junzhong said 68 testing sites were set up overnight for 220,000 community residents. "Hopefully we can finish testing in a day and a half," he said.

Zhengzhou has a population of over 10 million in China's most populous Henan Province.

All residents, as well as those paying a short visit to the city, such as rescue workers who came from all over the country to aid flood relief, must get tested.

The citywide testing is expected to be completed in three days.

"I was worried at the beginning. But I remembered we have Wuhan's experience in fighting an epidemic to learn from. Our government acted promptly," said Zhang Suping, a local resident.

"There's no need to worry about food and other supplies. Two weeks ago, torrential rains swept the city. We survived. So I think the government will take good care of us," said Feng Jiamei, another resident.

Zhengzhou has classified one area as high-risk for COVID-19 and three areas as medium-risk. 

According to a news briefing on Saturday night, most cases are patients, doctors and workers at Zhengzhou No. 6 Renmin Hospital.

Local authorities have acted swiftly to contain the spread. Residents say they hope the number of infections can be kept to a minimum.