As he approached a toll booth on the way to the airport, the police shot him dead.
Details of the incident are scanty. In today's Sydney Morning Herald, there is no official announcement as to a motive. A "diplomatic source in Beijing", according to the reporter, said that such random violence is commonplace in China.
Only Australian news outlets carried the story. More details emerged today after reporters talked with an Australian businessman who passed the bus and police in a taxi. Nick Hunt is general manager of Nufarm in China.
"The whole area between the toll gate and the bus was swarming with armed uniformed police and paramilitary types with dozen of vehicles," he said.
"The staff manning the toll gate were in a state of near panic and were just waving cars through.
"The actual hijacking was over by that stage and I saw no sign of the hijacker or hostages," the Shanghai-based Mr Hunt, said.
"Actually, the first thing that came to mind was they were making some type of movie, because every second person seemed to have a large video camera and microphone.
"They were doing interviews, filming marching troops in front of the bus and taking general footage of the scene.
"Quite surreal, actually. It wasn't until I got back to Shanghai and accessed foreign media that I found out what had transpired.
A friend who is Chinese says there is no story on the main Chinese-language websites.
Xi'an, a city in the centre of China, is described as in the "north-west" in extant stories. My friend says that anything north of the Yangtze River, for southerners, is northern China. Northerners tend to think of land located to the north of the Yellow River as 'northern China'.
The picture is of hostage Rhiannon Dunkley, of Corowa in NSW. Another picture, also in The Sydney Morning Herald, shows police "recounting the details". They are not "answering questions" is implied in this choice of words.
In the photo below, furthermore, there is nothing to indicate that it was taken in the Xi'an police offices. The sign at the back of the room says, simply, "press conference". "Chinese reporters are scared of these people," says my friend. "They have all the power."
According to the Herald, Xia "reportedly had a grievance with the Xian police (known as the Xian public service bureau or PSB)". In another story, we learn that Xia went to police headquarters "where the police chief exchanged himself for the hostages".
But Dunkley and "Eric" (the interpreter - more obscurity here) were kept by Xia for an unknown number of hours before Xia boarded the second bus. Dunkley was "on an educational tour with Australian travel agency China Bestours" when taken. She works at Corowa Travel Link.
The women were half-way through an "eight-day educational tour of Beijing, Shanghai and Xian". Jimmy Liu, from China Bestours in Sydney, says such tours are common.
Chinese authorities keen to downplay any security risks ahead of the August Olympic Games in Beijing have restricted reporting of the hostage drama and are believed to have seized footage and photographs of the siege in Xian's bustling Bell and Drum Tower square and at the airport.
Chinese officials and security officers also filmed the drama, but have refused to acknowledge or release any material.
None of the material Hunt saw being filmed has been released to the Australian media. On a quiet news day, the Herald gave it two columns at the bottom of the front page, with no photo. The photos here are from the Herald's website.
Coverage in China is scarce. Hua Shang Wang, a website associated with the Xi'an newspaper Hua Shang Bao, ran a story but it contains very little information. Hong Kong vehicle Da Gong Wang has more, but the Herald is more detailed.
The official website of the Xi'an newspaper has no story. Website www.chinareviewnews.com has almost exactly the same information as the Xi'an vehicles. Not indication of motivation is found.
Don't go looking on the BBC website for a story, either. They have headlined Sydney's mortgage stress, but this story - which is far more significant because it offers a window in the heavy wall of Chinese authoritarianism - gets no run.
Luckily, the Herald has thrown significant resources at the Xia Tao story. I've counted five reporters to date, including China-based (but Melbourne-raised Mary-Anne Toy.