The South Korean city of Daegu was facing an “unprecedented crisis” after coronavirus infections that centred on a controversial “cult” church surged to 38 cases, accounting for nearly half of the country’s total.

The city of 2.5 million people, which is two hours south of the capital Seoul, was turned into a ghost town after health officials said the bulk of country’s 31 new cases announced on Thursday were linked to a branch of the Shincheonji Church of Jesus.

“We are in an unprecedented crisis,” Daegu’s mayor, Kwon Young-jin, told reporters.

He ordered the shutdown of all kindergartens and public libraries, according to the news agency Yonhap. Schools in the city were considering postponing the beginning of the spring term scheduled for early March.

Shopping malls and movie theatres were empty and the usually busy city centre streets were quiet. A concert featuring BTS and other K-pop stars that was set for Daegu Stadium on 8 March has been postponed.

Medical staff move a patient suspected of contracting the coronavirus in Daegu. Photograph: Kim Jong-un/AP

The defence ministry banned troops stationed in Daegu from leaving their barracks and receiving guests. The US military imposed similar restrictions on its army base in the city, which houses thousands of troops, family members and civilian employees, curbing travel and closing schools and child care centres.

In what the Korean centre for disease control called a “super spreader” event, almost half of the country’s total of 82 infections have been linked to a 61-year-old woman who worships at the Daegu church, an entity often accused of being a cult.

She first developed a fever on 10 February but reportedly twice refused to be tested for the coronavirus on the grounds that she had not recently travelled abroad. She attended at least four services before being diagnosed.

So far, 37 other members of the church have been confirmed as infected.

Shincheonji claims that its founder, Lee Man-hee, has donned the mantle of Jesus Christ and will take 144,000 people with him to Heaven, body and soul, on the Day of Judgement.

Daegu’s municipal government said there were 1,001 Shincheonji members in the city, all of whom had been asked to self-quarantine, with 90 of them currently showing symptoms.

Those who have symptoms “will be tested as soon as possible”, Kwon Young-jin said, urging stronger action from the government in Seoul and calling the national response “inadequate”.

“We plan to test all believers of that church and have asked them to stay at home isolated from their families.”

The situation was “very grave”, South Korean vice health minister Kim Kang-lip said at a separate briefing.

Shincheonji said on Thursday that it had closed down all its facilities nationwide.

“We are deeply sorry that because of one of our members, who thought of her condition as a cold because she had not travelled abroad, led to many in our church being infected and thereby caused concern to the local community,” it said in a statement.

Agence France-Presse and Reuters contributed to this report