South Korea said on Saturday that the number of new coronavirus cases in the country had doubled to 433, and officials suggested that the tally could rise significantly as more than 1,000 people who attended a church at the centre of the outbreak reported flu-like symptoms.

Korea’s Centres for Disease Control and Prevention (KCDC) reported 142 new cases at a morning briefing and another 87 in the afternoon. KCDC also reported another death from the virus, bringing the total to three.

Of the new cases, most have been linked to outbreaks at a branch of the Shincheonji Church of Jesus in the southeastern city of Daegu and a hospital in Cheongdo county.

Samsung Electronics on Saturday said one of the virus cases had been confirmed at its mobile device factory complex in Gumi, causing a shutdown of the facility there until Monday morning. Gumi is close to Daegu.

Samsung’s factory in Gumi accounts for a small portion of its total smartphone production, as the world’s top smartphone maker produces most of its products in Vietnam and India. Also among the new cases were the first reported infections in Busan, South Korea’s second-largest city, and on the Island of Jeju, a popular tourist destination.

The government designated both Daegu, which has a population of 2.5 million people, and Cheongdo county, home to around 43,000 people, as “special care zones” on Friday. Officials sent military medical staff and other health workers, and extra resources, including hospital beds.

More than half of the national cases are linked to a 61-year-old woman known as “Patient 31” who attended religious services at a branch of the Shincheonji Church of Jesus in Daegu, the Temple of the Tabernacle of the Testimony. The woman had no recent record of overseas travel, authorities said.

KCDC said on Saturday they had obtained a list of 9,300 people who had attended church services, around 1,200 of whom had complained of flu-like symptoms.

The church and Cheongdo hospital outbreaks may also be linked, as several church members attended a funeral at the hospital for the brother of the founder of the church this month. President Moon Jae-in has called for officials to investigate potential links.

Cases from the hospital surged near a hundred overnight, with all but two of the new infections from the hospital’s psychiatric unit.

“We think the patients had repeated exposure given the isolated facility of the psychiatric wards, where many patients share the same room,” KCDC director Jeong Eun-kyeong told reporters.

The hospital, which has around 600 patients and staff, has been closed and patients are being transferred to other facilities.

Among the new confirmed cases were nine of the 39 South Koreans who had gone on a pilgrimage to Israel earlier this month, North Gyeongsang province governor Lee Cheol-woo told a briefing on Saturday.