An eight-second surveillance video posted on the city police force's Weibo account showed the two arguing and grappling with each other moments before the bus veered across oncoming traffic and off the bridge on Sunday morning.
The bus had veered into the wrong lane and collided with an oncoming vehicle in Chongqing on Sunday before it plunged into the Yangtze River. The video shows the pair swinging at each other, with the driver still attempting to steer the bus in between blows.
Police said the passenger, identified as a 48-year-old woman with the surname Liu, was angry that the bus had missed her stop. China's state newspaper, People's Daily, reports 15 people died in the crash.
The woman then used her mobile phone to strike the driver's shoulder, while the driver used his right hand to stop her attack and restrain her.
For days after the accident, the No. 22 bus lay at the bottom of the Yangtze River - in waters more than 70 meters (230 feet) deep. Authorities are still looking for the remaining two.
The bus was travelling at a speed of 51 kmph (31 mph) at the time of the accident, police said, adding that the investigation has ruled out any mechanical failure as a cause of the accident.
Xinhua News Agency reported that a floating crane pulled the wreck out of the river on Wednesday night.
The bus then lost control and veered onto the wrong side of the road and collided into an oncoming auto before breaking through fencing and flying off a bridge over the river.
As the quarrel escalated the woman hit the driver on the head with her smartphone, the statement added.
A Wanzhou police statement said the driver and the passenger broke the law with their actions because they seriously endangered public safety.