Senior Chinese security official Meng Jianzhu Sunday morning local time visited injured civilians and families of the deceased in the Saturday terrorist attack in the southwest Chinese city of Kunming.

Meng, head of the Commission for Political and Legal Affairs of the Communist Party of China Central Committee, said the case was a grave violent terrorist attack that caused untold damage to people's lives and property, urging timely treatment for the injured and assistance for the families of the deceased.

Meng investigated the crime scene at the station square, where he also listened to the report of local officials handling the case. The terrorists are conscienceless and extremely brutal, Meng said, adding that the sins of the attackers are unbearable. Meng said that relative departments should spare no effort in investigating the case, catching the assailants at large with all-out efforts, and punishing them in line with the law, in order to safeguard the sanctity of the law and ensure social stability.

Guo Shengkun, Chinese state councilor and minister of public security, also arrived in Kunming Sunday morning local time to guide work regarding the case.

President Xi Jinping has urged law enforcement to investigate and solve the case of Kunming terrorist attack with an all-out effort and punish the terrorists in line with the law, Xinhua News Agency reported. He paid tribute to the victims of the attack.

Premier Li Keqiang urged police across China to strengthen public security measures at all levels.

As the death toll from Saturday's terrorist attack at Kunming Railway Station in Yunnan province rose to 29 and the number of injured topped 130, the search for the perpetrators continued.

On Sunday, Kunming's government said evidence at the scene indicated that the attack was committed by terrorists from the Xinjiang Uygur autonomous region. If so, it would be the latest in a string of attacks related to the autonomous region, including incidents in January and February.

More than 10 masked people, dressed in identical black outfits and wielding large knives, stabbed and slashed passengers in the station's square and ticket hall. The attack began at 9:20 pm on Saturday and lasted about 12 minutes, according to China Central Television.

Police killed four of the assailants at the scene. Their identities have yet to be established. One woman was arrested.

There was a heavy police presence at the station on Sunday. The bloodstains had been washed away and passengers had returned to the busy transport hub. Flowers had been laid at the base of a bronze sculpture in the center of the square. Police had placed unclaimed luggage in a corner of the station, but some of the owners will never reclaim their belongings.

On Sunday, Lyu Xinhua, spokesman for the Second Session of the 12th National Committee of the Chinese People's Political Consultative Conference, told a media briefing that the attack exposed the "anti-human and anti-social" nature of the perpetrators and said they will be severely punished.

Ban Ki-moon, the UN secretary-general, strongly condemned the attack. In a statement released on Sunday, he said there was no justification for the slaughter of innocent civilians and hoped that those responsible will be brought to justice.

The UN Security Council also issued a statement to condemn the attack "in the strongest terms". Members of the council "reaffirmed that terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security, and that any acts of terrorism are criminal and unjustifiable regardless of their motivation, wherever and whenever and by whomsoever committed".

The United States was shocked and condemned by the brutal violence that caused heavy casualties, said the US State Department and the US Embassy in Beijing.

The Chinese community in the US was in shock hearing the news.

Chen Xianzhong, chairman of the New York Alliance for Defending the Diaoyu Islands, said that the violence is "simply terrifying".

"It is unforgivable to do such a thing to innocent people, regardless of the reasons behind it, especially when there are so many older people and children," he said. "At first I thought it was an outburst, but hearing that it was planned, I feel angry about it. It shouldn't have happened."

Through the Chinese Foreign Ministry and the Chinese Embassy in Washington, the US government extended its condolences to the deceased and voiced sympathy for the victims and their families.

The French Foreign Ministry said in a statement that France strongly condemns the bloody attack and said nothing can justify such acts.

It also extended its condolences to the victims' families and expressed solidarity with the government and the Chinese people.

The Russian President Vladimir Putin also condemned the attack.

Li Wei, director of the Anti-terrorism Research Center at the China Institutes of Contemporary International Relations, said that although the attack may have appeared to be a random incident, it was consistent with the tactics employed by terrorists, who constantly look for ways to penetrate poorly protected regions. He noted that the attack came just days before more than 5,000 national legislators and political advisers meet in Beijing for their annual sessions.

In Urumqi, Xinjiang's regional capital, and Beijing, authorities have long been aware of the need for precautionary measures, but Kunming is relatively weak in this regard, he said, adding that the use of identical clothing and weapons suggested that the attackers had spent a long time training and preparing for the attack.

He said the fight against terrorism should be guided by an overarching plan that implements concerted measures nationwide.

"This time it was Kunming, but it's impossible to say where it the next attack will occur. We can't rule anywhere out," he said.

For some of the survivors, the injuries were both physical and mental.

On Sunday morning, Wang Xianlong, 61, lay in bed at Kunming No 1 People's Hospital after spending five hours in surgery while doctors stitched up a 20-cm-long stab wound in his abdomen.

When the attack started, Wang Xianglong, a migrant worker from Baoshan city in Yunnan, and other passengers were waiting to board a train to Hebei province in North China. Wang Dezhu, one of Wang Xianlong's colleagues, said several migrant workers used bamboo hookah pipes to fend off the attackers.

Wang Xianlong wasn't aware he had sustained a deep cut to his abdomen, according to Wang Dezhu, who cared for many of the injured.

"I clearly saw his intestines coming out. He caught them and held them in place until the ambulance came to our aid," said Wang Dezhu. "Our colleagues are mostly in their 50s or 60s and they can't stand up to attacks like this. It's not safe out there anymore and we won't go to Hebei or any other province just to make money."

Wang Yangsheng from Guangzhou in Guangdong province, who was on a business trip, was buying a ticket at the station when the attack started. "I was facing the machine. Who could imagine that someone would slash me from behind?" said the 31-year-old, who sustained minor injuries.

He said the hospital was full of the injured by the time he arrived and the medical staff was racing to treat the victims. "I didn't have to pay for the treatment, and the authorities even provided free food," he said.

Although his wife is planning to fly to Kunming to look after him, Wang Yangsheng said he won't feel safe until he is at home. "I hope I can recover quickly and leave this place as soon as possible."

Yunnan University student Wu Jiangli was being treated for head injuries. "Whenever I close my eyes, the bloody scene comes into my mind again. My head is full of people's screams and blood. My physical injuries aren't serious, but a lot of mental harm has been done," she said.

Ma Juan, a student at Dali Medical College who was slashed across the head, said she was heading back to school in Dali, about 350 kilometers from Kunming, when the attackers appeared. "My head was slashed by a knife just as I began to run. Everything happened so quickly that I didn't even see the person who injured me. Fearing I might be struck again, I ran out to the road to call for help. I was in severe pain," she said.

With the help of passersby, Ma was taken to hospital. When she learned that 29 people had died and more than 120 had been injured, she said nothing, she just cried.

Saturday's attack was the most serious incident in China since 2009, when 197 people died in a riot in Urumqi.

In June last year, 24 people were killed and 23 injured in an attack in Lukqun Township, Turpan prefecture in Xinjiang. Local police said the suspected leader of the gang arranged for members to watch videos promoting religious extremism, and in the days before the attack, terrorists from Kuqa county in the south of the region called on the gang to carry out a jihad, or holy war.

On April 23, 15 people were killed in an attack in Selibuya township in south Xinjiang's Kashgar prefecture. Police said members of a terrorist cell regularly attended meetings where they studied material relating to religious extremism and terrorism. They also underwent physical training and learned to kill by watching footage of terrorist attacks.

The spread of religious extremism has led to an increase in the number of attacks, said Ma Pinyan, a senior anti-terrorism researcher and deputy director of the Ethnic and Religious Studies Center at Xinjiang Academy of Social Sciences.

In January, Nur Bekri, chairman of the Xinjiang government, said preventing and eliminating religious extremism has become an important task for the region as it strives to maintain long-term stability.

Yang Shu, director of the Institute of Central Asia Studies at Lanzhou University in Gansu province, said Xinjiang-inspired terrorist activities outside the region began much earlier than is generally acknowledged. He said police in the provinces of Gansu and Hebei had foiled several planned attacks in recent years.

On Oct 28, a jeep was driven into a crowd at Tian'anmen Square in Beijing, causing five deaths and 40 injuries. Police found gasoline, knives and steel bars in the car, along with a flag decked with extreme religious slogans.

The police later said the crash was the work of the East Turkestan Islamic Movement, which the Chinese government describes as a terrorist organization.

Mei Jianming, a professor at People's Public Security University of China, said it's difficult to identify terrorists because they can easily lay down their weapons and blend in with ordinary citizens. Ease of transport also means that they can quickly flee to regions where they are unknown.

According to Yang, the mismanagement of domestic ethnic relations and a misunderstanding of religion have resulted in an increase in domestic terrorism.

Yang said China is currently witnessing a wide range of social transformations and the terrorists use social problems as a way of recruiting new members. The establishment of an innovative social management mechanism to resolve social conflict would be the most effective anti-terrorism measure, he said.

Li of the China Institutes of Contemporary International Relations said the government should make the establishment of a counter-terrorism early warning and prevention system a top priority. "No matter how effectively we handle the aftermath of attacks, ordinary people are the victims. We need to set up an effective anti-terrorism intelligence mechanism to prevent such atrocities from happening in the first place."

He also urged the upgrading of China's anti-terrorism legislation to allow the government to mobilize more resources to prevent attacks.

Bo Xiao, director of the legislative affairs commission of the Xinjiang Regional People's Congress Standing Committee, said the Xinjiang government is considering anti-terrorism legislation. So far, the NPC, the country's top legislative body, has not added a nationwide anti-terrorism law to its work plan.

In 1997, Chinese criminal law was amended to include organizing, leading or joining terrorist cells after "organized terrorist crimes began to surface in some parts of China", according to Liu Renwen, a researcher in criminal law at the Chinese Academy of Social Sciences. People convicted of these offenses face sentences of 10 years to life imprisonment.

On Oct 29, 2011, the NPC's Standing Committee passed the Decision on Issues Related to Strengthening Anti-Terrorism Work, which clarified the definitions of terrorist activities, organizations and terrorists. It also included a list of suspected terrorist organizations and their members.

Liu said, "China has been considering drafting a comprehensive anti-terrorism law since the September 11 attacks in the United States in 2001, but it was difficult to reach a consensus on certain issues. The 'decision' was the result of that."

Xue Dan, Li Yingqing and Yang Wanli in Kunming, Dong Fangyu, Yang Yang, Zhang Lei and Zhang Yan in Beijing, Gao Bo in Urumqi, Zhang Yuwei, Amy He and Zhang Yang in New York and Xinhua contributed to this story.