Members of three amateur choirs stage a flash-mob performance at the China World Trade Center in Beijing. Photos Provided to China Daily

During lunch time, the food court at the China World Trade Center is a jumble of tension and chaos. Suddenly, it is quieted by the loud, sonorous voice of a woman singing. Suddenly, people young and old, wearing face mics, stand up from among the crowd and move toward the center of the space, all the while singing old songs that call forth people's common memories.

The 11-minute flash-mob performance soon turned into a party, with some watchers filming with their cellphones and others joining in the singing and dancing. A short film of this performance reportedly attracted more than 3 million hits within a week on video websites, and it generated some 9 million re-posts on Sina Weibo, China's major micro-blog platform.

Video: Flash-mob performance in Beijing

Feng Jinpeng, one of the performers and a member of CWTC workers' union choir, describes it as a once-in-a-lifetime experience. She used to watch flash mobs online but never expected to participate in one herself. She felt embarrassed and nervous at the beginning, but was soon overwhelmed by a feeling of warmth from the audience's reactions.

"We have a lot of white-collar people here. I seldom see them smile in normal situations, perhaps due to work pressure. You should see how breezily they smiled while watching the performance. It's so cozy," she says.

"You've got to take part in an event like this at least once in your life."

Such "action art" hasn't always been practical. The flash mob trend originated from New York in the early 2000s, where a man named Bill organized the first event featuring 500 people worshipping an animatronic T-rex dinosaur.

It soon caught on in China. One of the earliest was in Hangzhou in 2004, when some 400 people gathered in an open space to drink cola together. Better-known was a series of flash-mob dances organized by Chinese fans in recent years as part of a global campaign in memory of Michael Jackson.