Last June in the news was reported incident where Chinese marine surveillance vessels severed the exploration cables of a Vietnamese oil survey ship, first on May 26 and again in a similar incident in early June. A video of the incident was released by the Vietnamese government.

Now an other video of the incident has been released through a
Vietnamese video site showing there was also a collision between a Chinese and a Vietnamese patrol boat: (description translated from Chinese by
Google): China's marine surveillance ship violated Vietnam's exclusive
economic zone, so the Vietnam Marine Police boat attack on the Chinese
marine surveillance ships. May 26, Vietnam claimed that China's marine
surveillance ship violated Vietnam's territorial sovereignty, resulting
in economic losses, and impede the Vietnam National Oil and Gas Group
(PetroVietnam) operation.