China will spare no effort to seek justice for a "terrorist attack" at a crowded train station, its domestic security chief said, after militants were blamed for violence that killed at least 29 people.
Authorities said a group of knife-wielding "terrorists" from the region of Xinjiang launched a "premeditated" attack at the Kunming Railway Station in China's southwest on Saturday night.
More than 130 people were also wounded.
Police shot four of the attackers dead and captured one, state news agency Xinhua reported.
It quoted the Kunming city government as saying evidence at the crime scene showed the attack was carried out by Xinjiang separatist forces.
About five others were on the run, it said, after one of the worst attacks of its kind in China in recent memory.
It marks a major escalation in the simmering unrest that has centred on the heavily Muslim region in China's far west, strategically located on the borders of Central Asia.
"This brutal attack on defenceless, innocent people by violent terrorists devoid of conscience exposes their inhuman and anti-social nature," Xinhua quoted security chief Meng Jianzhu as saying.
"They inevitably will face the severe punishment of the law. We must mobilize all resources and adopt all means to break this case," Meng said, echoing comments made by Chinese President Xi Jinping.
Meng, who is also a member of the ruling Communist Party's elite 25-member Politburo, made an emergency trip to Kunming, where he visited wounded victims in hospital and went to the train station where the attack occurred.
The violence comes at a sensitive time as China gears up for the annual meeting of its largely rubber-stamp parliament, which opens in Beijing on Wednesday and is normally accompanied by a tightening of security across the country.
It is the first time people from Xinjiang have been blamed for carrying out such a large-scale attack so far from their homeland, and follows a smaller attack in Beijing's Tiananmen Square in October that shook the Communist Party leadership.
China stepped up security in Xinjiang after a vehicle ploughed into tourists on the edge of Tiananmen Square, killing the three people in the car and two bystanders. China labelled it a suicide attack by militants from Xinjiang.
Xinjiang is home to the Muslim Uighur people, many of whom chafe at Chinese restrictions on their culture and religion.
Kunming, the capital of Yunnan province, is hundreds of miles from Xinjiang and has little connection to the recent violence there that has killed more than 100 people in the past year.
China bristles at suggestions from exiles and rights groups that the unrest is driven more by unhappiness at government policies than by any serious threat from extremist groups who want to establish an independent state called East Turkestan.
One senior member of an advisory body to the soon-to-convene parliament said such attacks in China had foreign links.
"The well-planned attack was not an issue of (ethnicity) or religion, it was an issue of terrorism with links to the terrorist forces out of the country," Xinhua quoted PLA Navy Rear Admiral Yin Zhuo as saying.