Eight second-year students from a middle school at Huizhou City in southern Guangdong Province were organising a barbecue by Dongjiang River, when one of them accidentally fell into the river, according a police statement.
Four other students linking hands attempted to reach the drowning pupil but they too fell into water, state-run Xinhua news agency reported.
The three remaining students on the bank reported the case to the police and a rescue team rushed to the scene.
The bodies of all five students were retrieved.
The vessel - Xinchuan 8 - collided with one of the piers of the Nanjing Yangtze River Bridge when it was trying to pass through.