An attacker in China stabbed five people to death on Friday before being shot dead, authorities said, ruling out terrorism two weeks after 29 people were killed in a mass stabbing blamed on Xinjiang militants that stunned the nation.

A vendor in a market fatally attacked another during an argument, then stabbed four bystanders before officers killed him, police in Changsha in the central province of Hunan said on their verified account on Sina Weibo, a Chinese version of Twitter.

Two of the bystanders died at the scene while the two others succumbed later in hospital, it added.

A Changsha official told AFP by phone: "I can assure you it's not a terror attack. It happened in a market due to some dispute."

The Hunan Evening News said the vendors came from China's far-west Xinjiang region, home to China's mainly Muslim Uighur minority, but their ethnicity was not confirmed.

It added that two people, including one woman, had been detained, while the official news agency Xinhua reported that a "group of knife-wielding assailants" were involved.

One victim was an elderly woman in her 80s who had just walked on to the street, a Hunan radio station reported.

Photos posted on Sina Weibo -- whose authenticity could not be verified -- appeared to show the bloodied bodies of three men on the ground, with armed police and bystanders nearby. Another showed a man being taken away by officers.

- Periodic unrest -

The incident came after a group of attackers went on a stabbing spree at a railway station in the southwestern city of Kunming in Yunnan province on March 1, leaving 29 people dead and 143 injured in what domestic media have dubbed China's "9/11".

Four assailants -- some wearing black with their faces covered -- were shot dead at the scene. One woman was detained on site and three others were arrested separately.

Authorities condemned the event as terrorism and blamed it on militants from the restive Xinjiang region.

Violent attacks by Uighurs are periodically reported in Xinjiang -- usually targeting police or government officials and labelled by authorities as terrorist attacks -- but they rarely occur outside the remote area.

Beijing says it faces a violent separatist movement driven by religious extremism, but critics accuse it of exaggerating that threat to justify hard-line measures.

Rights groups also accuse the authorities of cultural and religious repression that feeds dissent, while China counters it has invested heavily in economic development in the region, which covers a sixth of the country's territory and is rich in natural resources.

But much of the economic gain has benefited an influx of ethnic majority Han Chinese, and tensions between Han and Uighurs boiled over into riots in 2009 that left around 200 people dead.

In October last year China experienced its first high-profile incident outside Xinjiang pinned on residents of the area -- in Beijing's central Tiananmen Square, the symbolic heart of the Chinese state.

Three family members drove into crowds of tourists and set their car ablaze, killing themselves and two bystanders. Within a day police arrested five suspects, all from Xinjiang.

Information about such events is restricted to reports by authorities and state media, which are often limited in detail and hard to verify independently.