HOHHOT -- The border city of Erenhot in north China's Inner Mongolia autonomous region started all-inclusive nucleic acid testing on its residents on Thursday noon after it reported one locally transmitted COVID-19 confirmed case the same day.

The new local infection tested positive for the coronavirus on Tuesday during routine testing on the staff of a logistics park. All the other 31 staff members under closed-off management in the park tested negative for the virus the next day, according to the local epidemic prevention and control headquarters.

The patient was reported as a local case by the city's health authorities Thursday and sent to the hospital for further observation and medical treatment.

Relevant epidemiological investigation and environmental disinfection efforts are still underway. All the contacts of the case have been quarantined and put under medical observation.

The first round of this mass testing is expected to complete by the end of the day.

Meanwhile, the city has imposed closed-off management on all the areas it administers and tightened control over traffic at its entrances and exits. The city's government agencies, enterprises, and public institutions have suspended work and production activities, while schools and kindergartens have suspended classes.

Currently, the city's water, electricity, oil, gas, heating, communications, and other basic livelihood supplies remain functional and relevant departments will stay on duty to ensure regular operation of the facilities.

Erenhot Port is the largest land port on the border between China and Mongolia.