The unrest at a Singapore-run industrial park followed large anti-China protests by workers at the park and nearby areas.
It shows the danger for authorities in Vietnam as they seek to handle public anger over China's deployment of an oil rig on May 1 in South China Sea waters that Hanoi claims as its own.
The rioters attacked factories they believed to be Chinese, but many were Taiwanese owned. Then groups of men on motorbikes drove around the complex waving Vietnamese flags and work there was stopped, the official said.
At the height of the protests up to 20,000 people were involved, according to a foreign diplomat briefed on the unrest.
Vietnam reacted angrily to the arrival of the deep-sea oil rig on May 1 close to the Paracel Islands, which are controlled by China but claimed by Hanoi.