The Google.cn / Google.com.hk lockdown has begun: ALL search queries now end in a connection reset

Try searching for anything inane at all on Google.cn or Google.com.hk (otherwise known as the “new home of Google.cn”) and you will now get a connection reset. We tried searching for “shanghai” and all we got was the white screen of death.
Thanks Net Nanny! Now we finally know what One Country, Two Systems really means!
Update #1, 7.48pm:
@gfwrev tweets here and here and here: 此次中国大陆google被封的罪魁祸首：.google. && rfa // 因为普通搜索存在 &gs_rfai= 语句, 其中rfa和某被墙的关键词重合. // 这次Google被封锁只是GFW整理Google系列关键词时的一个乌龙。
The ultimate culprit for Google’s block in mainland China are the terms “.google.” and “rfa”. One of the search parameters includes the term “&gs_rfai=” and RFA stands for “Radio Free Asia”, a site that is blocked in China. This apparent block is just a boo-boo on Google’s part. [To that we say, O RLY? Why didn’t it happen earlier?]
Update #2, 8.14pm:
@SirSteven in Suzhou and @CatShanghai from around Nanpu Bridge in Shanghai note that Google.cn is still working from where they are.
Update #3, March 31, 12.30pm:
Google.cn and Google.com.hk back to normal. And search terms like “communism” returned full results, even with the “&gs_rfai=” parameter. Weird. Was the Net Nanny testing new machines?