Pakistan has quarantined 20,000 attendees of an Islamic gathering in Lahore last month and is still searching for tens of thousands more, officials said on Sunday.

Over 100,000 worshippers congregated at the event, defying government orders to call off the gathering amid coronavirus fears.

Pakistan’s science minister, Fawad Chaudhry, reportedly expressed exasperation that the event had been held as planned. He blamed the “stubbornness of the clergy” for dismissing official orders to halt the large gathering. Organizers claimed to have cut the event short following advice from the authorities; however, at the time of the event, they said it was due to inclement weather.

The meeting took place between March 10-12 in Lahore, Pakistan’s capital. It was organized by Tablighi Jamaat, a global “Islamic missionary movement” with millions of followers, especially in South Asia. The far-reaching Sunni group promotes proselytizing, known as dakwah.

So far, officials have confirmed that at least 145 people were infected with the Chinese coronavirus from the event in March; two people have died. Authorities hope to test or quarantine attendees.

People from China, Indonesia, Nigeria, and Afghanistan also attended, which has resulted in about 1,500 foreigners now being quarantined in Pakistan. Others left the country without being tested.

In March, Gaza’s health ministry confirmed that its first two cases of coronavirus were Palestinians who had attended the Tablighi Jamaat gathering in Lahore.

Similar Tablighi Jamaat events held in Malaysia and India during the coronavirus pandemic have been blamed for spreading the coronavirus to other regions.

At press time on Monday, Pakistan had reported 3,766 infections and 53 deaths from the Chinese coronavirus.