The accident happened in the early hours when two cargo ships collided.
A total of 13 people fell into the waters. So far rescuers have pulled out four people, and found three bodies. They are still searching for the remaining six, state-run Xinhua news agency reported.
The two ships, "Andasheng" and "Xindongyuan", belonged to companies from north China's Hebei Province and east China's Anhui Province, respectively. "Xindongyuan" sank in the accident.