CHONGQING, May 9 (Xinhua) -- Three people are missing after a boat capsized in the Yangtze River as it was berthing at a dock in southwest China's Chongqing Municipality on Tuesday, according to the municipal maritime office.

The boat, belonging to Jinsha Shipping Co. Ltd., capsized about8:00 p.m. on Tuesday in the Jiangjin section of river as it was carrying 330 tons of cobblestones from the northern to the southern bank.

All the six crew members and porters fell into water. Three were rescued, but the other three are still missing, said rescuers.

Initial investigations have attributed the cause of the accident to crew errors.