South Korea raised its infectious disease alert to its highest level on Sunday, as confirmed coronavirus cases in the country jumped to 602 and the death toll rose to six.

More than half of the new cases are linked to a church in the southeastern city of Daegu, after a 61-year-old woman known as “Patient 31” who attended services there tested positive for the virus last week. The woman had no recent record of overseas travel.

South Korean President Moon Jae-in said on Sunday that the government had raised the country’s disease alert by one notch to the fourth and highest level in a bid to contain a surge in new cases.

The Korea Centers for Disease and Control and Prevention (KCDC) said the number of infections had jumped by 169. Of the total confirmed cases, more than 300 were linked to the Shincheonji Church of Jesus congregation in Daegu.

The escalation in the alert level allows the government to send extra resources to Daegu city and Cheongdo county, which were designated “special care zones” on Friday.

The alert level also enables government to forcibly prevent public activities and order the temporary closure of schools, the health ministry said.

“The coronavirus virus is more contagious and spreads quickly during the early stage of the outbreak, and therefore preemptive measures are needed considering a possibility that the virus could develop to a nationwide spread from a community spread,” health minister Park Neung-hoo told a news conference.

“We believe a week to 10 days will be crucial to determine the spread of the coronavirus.”

The last time South Korea raised the alert level to “red” was 11 years ago during the Influenza A or H1N1 outbreak, South Korea’s Yonhap News Agency said.

Since the first confirmed case on January 20, six people have died from the virus in South Korea, with three deaths reported on Sunday.