"He was dying when the ambulance arrived," one of the onlookers said.

Police arrested Xu on the same day on suspicion of murder, said Xiong Lu, a procurator with Haidian District Procuratorate. "It was an act of murder rather than manslaughter, because Xu had apparently killed Sun intentionally."

Xu, 26, was from Baoding city in the neighboring Hebei Province.

Almost a week after the tragedy, online discussion still continued Saturday, with suggestion for "human flesh search" -- a massive Internet searching aiming to identify and expose Xu to public humiliation.

Most web users bombarded Xu as "cold-blooded" and "rampant", while some others suggested he was simply a victim of mounting pressure in a fast-paced society.

"I don't think we can blame the society or high pressure for such cruelty," said Professor Li Meijin with Chinese People's Public Security University. "It's an act of sheer apathy and shows the offender lacks moral decency."

An online poll by Sohu.com, however, showed 61 percent of the 10,835 respondents had symptoms of "road rage". They said they often angrily slammed the horn, yelled and occasionally ended up fighting with others when the traffic moved too slowly or when their lane was blocked by other vehicles or pedestrians.

Procuratorate offices in nearly all downtown Beijing districts claim they are handling a growing number of disputes among angry drivers themselves and between drivers, cyclists and pedestrians.

"Most of the disputes could have been solved easily with an apology and compromise before escalating into violence," said Xiong Lu, a procurator who was handling Xu's case.

Professor Li, who was also a specialist on juvenile delinquency, said driving schools should enhance moral education for new drivers. "As China's motor vehicle fleet keeps expanding, it's crucial for the drivers to be more tolerant and respect lives."