Zhang said he headed to Wang's home at around 7pm on Sunday after hearing about the raids but the pastor and his wife Jiang Rong were nowhere to be found.
"His home was ransacked. It was a mess," Zhang said.
"The police said our church is an illegal organisation and we cannot attend any more gatherings from now on."
The Early Rain Covenant Church is one of China's few unofficial house churches - Christian assemblies that operate without state sanction - and this is not the first time Wang and other members of the church have been detained.
While most of China's Protestant house churches operate underground to avoid attracting official attention and control, the Early Rain congregation openly practises its faith, posting sermons online and evangelising on the streets.
Many house churches have been closed this year in China's harshest religious suppression in decades.
Bob Fu of China Aid, a US-based Christian non-profit organisation, said the crackdown represented a major escalation of religious persecution in China.
According to Fu, there were more than 10,000 cases of detention of Christians this year, compared with just over 3000 cases for the whole of last year. In September, Beijing police closed the Zion Church, one of the largest Protestant churches in China with more than 1500 regular church-goers.
In February the Religious Affairs Regulation was amended to give grass-roots officials more power to act against churches and impose tougher penalties for "unauthorised religious gatherings".
Chinese Arabic school to close as areas with Muslim populations are urged to study the Xinjiang wayIn Henan and Zhejiang provinces, two of the hardest-hit areas in the religious clampdown, churches have been shut down or even demolished, and their members told to denounce their faith.
The Early Rain church has about 500 followers but their weekly gatherings spread across 12 meeting points around Chengdu, attracting more than 800 church-goers on a weekly basis, according to the church's elders. It also has about 100 seminary students and a primary school catering to about 40 children.
The South China Morning Post has learned that a number of elders are still in hiding while many church members were tracked down by police overnight asking them to sign a letter pledging they would not attend further gatherings.
"This round of crackdown is unusual as it seems that the authorities want to close the church down for good. Our social media channel accounts such as WeChat were not closed in previous rounds and they have taken a large number of our members into custody this time. The scale was unprecedented," said Li Yingqiang, one of the church elders.
Despite the massive purge, Li said gatherings would continue.
"Even if we are down to our last five, worship and gatherings will still go on because our faith is real," Li said.
"Persecution is a price worth paying for the Lord. We would rather live through it than to hide our faith and we hope more Chinese churches will speak up and stand with us."
- South China Morning Post