Fishermen in the central province of Quang Nam said their boat was rammed and sunk by a Chinese coast guard ship while they were fishing near the islands of Hoang Sa (Paracels) Tuesday night.
Captain Pham Phu Thanh, 50, told local authorities that his boat with four people aboard was around 370 nautical miles from Da Nang at around 11 p.m. when the Chinese ship attacked it.
Thanh said after his boat sank, he and the other three jumped into the sea.
Thirty other members of the crew who were fishing close by on small coracles were safe, the captain added.
Several hours after the Chinese vessel left, another Vietnamese fishing boat near the site approached and rescued the whole team of 34. A rescue ship arrived soon later.
The crew was taken home late on Thursday.
Authorities said they are investigating the incident.
China has claimed Vietnam’s Hoang Sa and Truong Sa (Spratly) archipelagos as its own.
Chinese fishing boats and coast guard ships have reportedly attacked and harassed Vietnamese fishermen many times.
Vietnam has repeatedly criticized these acts and reaffirmed its sovereignty on both Hoang Sa and Truong Sa (Spratly) archipelagos.