At least 33 people were killed and more than 140 wounded after a group of knife-wielding attackers dressed in black went on the rampage in a Kunming railway station, hacking and stabbing passengers and passers-by indiscriminately. The death toll includes 29 civilian victims killed by the attackers and four alleged assailants shot dead by responding police, according to state media. One injured policeman was reported to have died on Sunday afternoon, said China's ministry of public security, although it later withdrew the confirmation. Online postings by witnesses said the attackers took out long knives and began hacking “crazily” at people shortly after 9pm on Saturday, chasing terrified victims through the station, leaving bodies in their wake. Watch: Xinjiang separatists behind deadly China rail attack: Xinhua Horror at the railway station: eyewitnesses tell of Kunming slaughter State broadcaster CCTV said earlier that three of the four alleged attackers killed by police were male, and one female. Another female suspected was wounded by police fire and sent to a hospital for emergency surgeries, it said. Some eyewitness accounts on social media say there were more than a dozen attackers. On Sunday, Xinhua quoted Kunming officials as saying that initial investigations suggested the deadly attack was "planned and organised by separatist forces from Xinjiang," the restive western autonomous region which has seen many similar attacks against civilians and police in recent years. Chinese President Xi Jinping called for "all-out efforts" in the investigation and for the attackers to be punished "in accordance with the law", Xinhua said. "Understand the serious and complex nation of combating terrorism. Go all out to maintain social stability," it quoted Xi as saying. China's top security official Meng Jianzhu, who arrived in Kunming early on Sunday morning to oversee the police investigation, said: "All-out efforts should be made to treat the injured people, severely punish terrorists according to the law, and prevent the occurrence of similar cases, to ensure the safety of people's lives and property and social stability." Secretary-General Ban Ki-moon of the United Nations on Sunday strongly condemned the attack. “The Secretary-General notes that there is no justification for the killing of innocent civilians and hopes that those responsible will be brought to justice,” said a statement released by the United Nations. The attack came ahead of the opening of the Chinese People’s Political Consultative Conference (CPPCC) on Monday and the National People’s Congress on Wednesday. This is traditionally the most politically sensitive time of the year, with the government eager to maintain stability and paint a rosy picture as thousands of delegates and government leaders head to the capital. One knife victim named Yang Haifei, who was wounded in the chest and back, told Xinhua that he had been buying a train ticket when the attackers approached and had tried to escape with the crowd. "I saw a person come straight at me with a long knife and I ran away with everyone," he said, while others "simply fell on the ground". Some who had escaped were desperately looking for missing loved ones. "I can't find my husband, and his phone went unanswered," Yang Ziqing was quoted as saying. She said she had been waiting for her train to Shanghai "when a knife-wielding man suddenly came at them". State television showed police wrapping a long, sword-like knife in a plastic bag, amid heavy security at the station. Graphic pictures posted on weibo showed victims lying in pools of blood inside and outside the station, while others showed blood, luggage and clothes scattered on the floor of the ticket hall. Such violence is extremely rare in Kunming, the usually peaceful capital of Yunnan. One online posting said the attackers had been five young men dressed in black uniforms. The police did not specify their number, or their ethnicity or motives, although some online postings alleged they were Uygurs. A hotel worker told the Sunday Morning Post last night she heard the same rumour from people who took refuge in her hotel. “People are rushing towards our hotel. We heard that the attackers are dressed in black, and they are Uygurs.” Although the police said they shot dead the assailants she said the city was in panic. “Our guests who walked passed the train station told us not to leave the hotel because the situation is dangerous. We dare not leave the hotel right now. There are many police outside. We just fear that not all the attackers have been caught.” A microblogger named “HuangY3xin-Dione”, who was dining in a restaurant near the station, said she was “scared to death”, adding that she saw a group of men in black with two long knives chasing people. Another hotel employee told the Post that a number of roads had been cordoned off. President Xi Jinping and Premier Li Keqiang sent condolences to the victims and their families. China has been hit by a series of violent incidents in recent months, but most of them were in restive Xinjiang, with authorities blaming Uygur separatists. Incidents involving Uygurs are often labelled "terrorist attacks" while others carried out by Chinese seen as having grievances against society or the authorities are not. In a high-profile incident in Beijing last October, three Uygur family members set their car on fire at Tiananmen Square, the symbolic heart of the Chinese state, killing themselves and two bystanders. Hu Xijin, editor of the influential Global Times newspaper, published by the ruling Communist Party's official People's Daily, wrote on his Weibo feed that the government should say who it suspected of the attack as soon as possible. "If it was Xinjiang separatists, it needs to be announced promptly, as hearsay should not be allowed to fill the vacuum," Hu wrote. =========================================================== Chronology of key events related to the restive region since 2009: 2009 June 25 Two Uighur factory workers are reported killed and dozens injured in a huge brawl with Han Chinese in Shaoguan, in the southern province of Guangdong. July 5 Hundreds, perhaps thousands, of Uighurs riot in the Xinjiang capital Urumqi after security forces move in on a protest over the Shaoguan incident. July 7 The government says nearly 200 people died in the unrest, with more than 1,600 injured and hundreds arrested. Eventually at least 26 are reportedly sentenced to death. September 2 -- Han residents of Urumqi protest for days over a wave of syringe stabbings which the government eventually says had nearly 500 victims, blaming “ethnic separatist forces”. 2011 July 18 Police kill 20 protesters in clashes in Hotan, southern Xinjiang, exiled Uighur groups say. State media say police fired on demonstrators who attacked a police station, killing one officer. July 31-August 1 Two attacks by alleged terrorists leave 13 people dead in a Han Chinese section of Kashgar, while police kill eight suspected Uighur separatists. September 15 Courts in Xinjiang sentence to death four Uighurs over the July incidents. December 28 Police in Pishan kill seven “terrorists” in a hostage standoff that left one officer dead. State media calls them terrorists engaged in a “holy war”. 2012 February 28 Rioters armed with knives kill at least 10 people in Yecheng, while police shoot two of the attackers dead, state press say. One man is later sentenced to death. 2013 April 23 Gunfights in Bachu leave 15 police and community workers and six “terrorists” dead. Two men are later sentenced to death. June 26 At least 35 people are killed when, according to Xinhua, “knife-wielding mobs” attack police stations and other sites in Lukqun before security personnel open fire. Three people are later sentenced to death. August 20 A Chinese policeman is killed in what state media call an “anti-terrorism” operation in Yilkiqi. Overseas media report 22 Uighurs were shot dead. October 28 Three members of the same Xinjiang family crash their car into tourists in Tiananmen Square in Beijing, the symbolic heart of the Chinese state, killing two, before setting it on fire and dying themselves, according to authorities who call it a terrorist attack. November 17 Two policemen and nine attackers are killed at a police station in Serikbuya, state media say. Rights groups say the trigger was the fatal shooting of a Uighur youth during a protest. December 16 14 Uighurs and two police officers are killed in Shufu county. Authorities describe the slain Uighurs as members of an extremist group, but campaigners say police raided a house where a family was preparing for a wedding, with six women among those killed. December 30 An assault on a police station in Yarkand leaves eight attackers dead, according to the Xinjiang government’s official website. 2014 January 15 A prominent Uighur academic and critic of government policy, economics lecturer Ilham Tohti, is detained by police, his wife says, and later charged with separatism, which can carry the death penalty. January 25 A total of 12 people have been killed in Xinhe, six in explosions and six shot dead by police dealing with “violent incidents”, a government-run news portal says. February 14 A total of 11 people die in an attack on police in Wushi, with officers shooting eight dead and three blowing themselves up, authorities say. March 1 At least 29 people are killed and more than 130 wounded by knife-wielding assailants at Kunming train station in Yunnan province, more than 1,600 kilometres from Xinjiang. Officials blame separatist terrorists from Xinjiang.