During the fight, Ran lost control of the bus and the vehicle broke through a guardrail and plunged into the river with an estimated 15 passengers on board in Wanzhou, Chongqing.
Police examined nearly 2,300 hours of surveillance videos along the bus route to determine the cause of the accident which gripped the nation.
The bus suddenly veered into the wrong lane and collided with an oncoming vehicle on Sunday in Chongqing before it drove off the bridge. It doesn't look as if the driver had time even to hit the brakes before the bus went off the bridge.
The surveillance recording showed that at 10.03am, five minutes before the accident, the woman stood up from her seat, walked up to driver and began cursing him.
A search and rescue operation was launched on the Yangtze river near Chongqing in southwest China on October 28. The bodies of 13 people were recovered; two remain missing. The video shows the pair swinging at each other, with the driver still attempting to steer the bus in between blows.
The Wanzhou police statement said the behaviour of the driver and the passenger seriously endangered public safety and violated the law.
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.
Police said on Friday, Nov. 2, 2018, a brawl between a passenger and a bus driver was the cause of the bus plunging off a bridge and killing more than a dozen people in southwestern China on Sunday.