A pastor of a prominent underground church in China was detained, according to his daughter, a church pastor and a group that monitors religion in the East Asian country.

Pastor Ezra Jin Mingri of the Zion Church was detained at his home in Beihai in China’s southeast Guangxi province on Friday evening, along with dozens of other church leaders in Beijing and at least five other provinces across China. They may face charges of “illegal dissemination of religious content via the internet”, according to Sean Long, a Chinese Zion Church pastor currently studying in the United States.

“This is a very disturbing and distressing moment,” Long told The Associated Press by phone. “This is a brutal violation of freedom of religion, which is written into the Chinese constitution. We want our pastors to be released immediately.”

Long said he learned of the arrests from dozens of church leaders located in China who posted photos and videos of police entering church spaces in an online group chat.

Zion Church is among the largest so-called underground or house churches that are unregistered with the Chinese authorities. They defy Chinese government restrictions requiring believers to worship only in registered congregations.

The Chinese Foreign Ministry, the Ministry of Public Security, the department of religious affairs, and Beihai police did not immediately respond to requests for comment.

Under Chinese leader Xi Jinping, Beijing has cracked down on independent Christian congregations over the past decade, destroying crosses, burning Bibles, shuttering churches and ordering followers to sign papers renouncing their faith. Chinese authorities have pushed to “Sinicize” religion by demanding loyalty to the officially atheist Communist Party and eliminating any challenge to its power over people’s lives.

Jin’s daughter, Grace Jin, who lives in the United States, isn’t certain what prompted this recent crackdown, but she believes it may be because of the Zion Church’s growing influence and challenge to Communist Party rule.

“Zion blew up after COVID, so that irked the government,” she said.

Many underground churches were targeted during a nationwide crackdown in 2018, and Zion Church’s main sanctuary was shut down. But during the coronavirus pandemic, Zion Church membership grew after it held online prayer sessions, attracting believers who were unable to attend worship at government-sanctioned churches that often shut their doors due to pandemic restrictions.

The church’s membership grew from roughly 1,500 in 2018 to perhaps 5,000 or more members today, Long said, with over 100 worship sites in apartments, restaurants, and even karaoke bars in around 40 cities across China.

Other underground churches in China have also come under pressure in recent months.

In May, the pastor of Light of Zion Church in Xi’an in eastern China was detained. In June, ten members of the Golden Lampstand Church in the western province of Shanxi were sentenced to prison after being arrested four years ago.

“We are witnessing the most extensive and coordinated wave of persecution against urban independent house churches in China in over four decades,” said Bob Fu, founder of U.S.-based religious group China Aid, which also reported the Zion Church arrests.

Grace said that her father, Pastor Jin, had brought his family over to the United States after authorities targeted Zion Church in 2018. But he decided to go back despite the risks. She hasn’t seen her father in six years, she said.

“He felt that as a pastor he had to be with the flock,” she said, fighting tears. “He had always been prepared for something like this.”