The park allowed no visitors in or out, as workers wore white protective suits instead of the beloved Disney character costumes and every visitor closed in the park was tested. Once results were confirmed negative, the visitors were allowed leave.

According to local media, the case that might have caused the lockdown involved one person who had visited Disneyland on Saturday and was ill.

The city announced Monday that all of the 33,863 people in Disneyland on Sunday had tested negative for COVID-19, although they are asked to receive more testing and their health will be further monitored.

The theme park remains closed on Monday and Tuesday as it follows pandemic preventions, Shanghai Disneyland said in a statement Monday.

For more reporting from the Associated Press, see below.

Globally, many countries have turned to living with the virus, whether out of choice or necessity, although as virus surges come and go, many face overburdened health care systems and additional deaths.

In China, which has kept its borders sealed since March 2020, the response has been to cut the chain of transmission of the virus as quickly as possible. With a strict quarantine-on-arrival policy, the authorities have aimed to stamp out each local outbreak to zero—helping China keep its reported totals to 4,636 deaths and 97,243 cases since the pandemic began.

One Disney fan, who gave her family name as Chen, said she was inside the park when she heard an announcement at 5 p.m. that everyone must get tested.

“No one complained, and everyone behaved really well,” Chen said. She said she holds an annual membership and visits the park at least once a month. She is waiting at a hotel for her second COVID-19 test before she can go back to Beijing.

Shanghai Disneyland is just the latest example of how far Chinese authorities will go to stop the spread of the virus.

Last Thursday, Beijing Railway authorities told health authorities in Jinan to stop a train that was traveling from Shanghai to Beijing because one passenger was a close contact of someone who had tested positive for COVID-19.

Jinan health authorities then sent health care workers, transportation workers and police rushing to the station to quarantine the passengers and disinfect the train. They sent 212 people into centralized quarantine, including the close contact.