Churches were closed in South Korea on Sunday, with many holding online services instead, as authorities fought to rein in public gatherings as 586 new coronavirus infections took the tally to 3,736 cases.

That came a day after the biggest daily jump of 813 cases in South Korea’s battle with the largest virus outbreak outside China, the Korea Centres for Disease Control and Prevention (KCDC) said. The death toll rose to 20, up from 17 the day before.

In Seoul, the capital, about a dozen worshippers were turned away from the Yoido Full Gospel Church, which uploaded a sermon for its 560,000 followers on YouTube, filmed with a small choir instead of all 200 members and 60-strong orchestra.

“I had heard there would be no service, but just came to check as I live nearby, but yes, it is so empty,” said Song Young-koo, as he left South Korea’s biggest church.

“It’s a wise decision to do it online, since the virus would easily spread at mass gatherings and churches can be no exception.”

Authorities have warned of a “critical moment” in the battle against the virus, urging people to refrain from attending religious services and political events and stay home this weekend.

For the first time in its 236-year history, South Korea’s Catholic church decided to halt masses at more than 1,700 locations nationwide. Buddhist temples also called off events, while major Christian churches held online services.

Of the new cases, 333 were from the southeastern city of Daegu, the location of a church at the centre of the outbreak, and 26 from the nearby province of North Gyeongsang, the KCDC said.

The agency said some church members in January visited the central Chinese city of Wuhan, where the disease emerged late last year, adding it was investigating to determine if the trip played a role in the outbreak.