A major international airport in southern China near Hong Kong canceled more than 400 flights on Friday after a staff member at a restaurant inside the airport tested positive for the Chinese coronavirus, China’s state-run Global Times reported.

Canceled arriving and departing flights at Shenzhen Bao’an International Airport in Guangdong province on June 18 “accounted for around 40 percent of the total number of flights at the airport,” the Global Times reported, citing data from the Chinese flight information platformVariFlight. The canceled flights included “cancellations on Friday and cancellations in advance.”

“According to a notice issued by the Shenzhen airport epidemic prevention and control office obtained by the Global Times, a staff [member] at a restaurant in the airport tested positive for the virus, despite the person being vaccinated twice in January and February,” the newspaper reported. “The staff [member] previously tested negative on June 1, 7, 9 and 15.”

“The airport has asked 56 staff [members] working at the same restaurant to go into quarantine, the notice said, warning of the possibility it would cancel more flights. The airport has closed all stores and started the third round of mass nucleic acid testing,” according to the Global Times.

Shenzhen Bao’an International Airport is located just 60 miles southeast of Guangzhou, the capital of Guangdong province. Guangzhou Baiyun International Airport, one of the busiest international airports in China and the world, has been forced to cancel several hundred flights per day since May 30 because of a local outbreak of the Chinese coronavirus.

“As of 1:30 pm Sunday [June 6], the airport had canceled 892 flights,” the Global Times reported.

Guangzhou’s latest coronavirus epidemic started on May 21, quickly spreading at an “alarming” rate to the nearby cities of Foshan and Maoming, the South China Morning Post reported at the time. Guangzhou health authorities ordered Guangzhou’s Liwan district into lockdown on May 29 after allegedly tracing the city’s outbreak to a woman who had recently dined at a local dim sum restaurant. The stringent lockdown orders came after Guangdong health officials said they had detected just 20 cases of the Chinese coronavirus in Guangzhou and its surrounding area, which is home to nearly 14 million people.

Municipal government officials announced on May 30 that all people attempting to travel out of Guangzhou must show proof of having tested negative for the Chinese coronavirus within the past 72 hours before they would be allowed to leave the metropolis. Guangzhou updated this travel restriction on June 7, requiring travelers to present a negative coronavirus test result taken within 48 hours of leaving the city. The testing requirement was also expanded to all of Guangdong province as local coronavirus infections continued to surge.

“We call on our residents not to travel out of the province unless necessary. Those who need to travel out of the province must have a negative test done 48 hours before their departure,” Chen Bin, a spokeswoman for the Guangzhou Health Commission, told reporters at a June 6 press briefing.