Security was tightened at South Urumqi train station one day after the blast that killed three people and injured 79 others in a suspected terror attack, with an increased armed police presence. Dozens of armoured vehicles were stationed on Thursday afternoon at entrances to the largest railway station in Urumqi, capital of Xinjiang, with hundreds of gun- or shield-wielding uniformed officers patrolling the railway complex. The station exit, where the blast took place, was cordoned off on Thursday, leaving many onlookers, both Han and Uygur, standing by solemnly and quietly exchanging words about the attack. “Some people were chopping others with their knives, and then came the sound of the explosion, which was deafening,” said a shop worker at a mobile phone accessories shop. “I ran away without thinking, but I saw several men lying on the ground, heavily injured.” she said. She added that she did not clearly see how many assailants there were, or how they were dressed. All I heard was the explosion and screams, and all I saw were several people hurt Bystander “We were waiting outside the station for a train to Yili, and then the bomb exploded. Many pieces of luggage were scattered around. I then saw a man whose leg was seriously hurt, limping out of the station," a traveller from Wuxi said. He added that his train on Wednesday night had been cancelled following the attack, and he had come to Urumqi station again on Thursday in hopes of getting a train out of the city. “All I heard was the explosion and screams, and all I saw were several people hurt. And then I ran away as fast as I could,” a grocer said. “I heard the loud blast and ran for my life. People in other shops did the same. We were then asked not to open for the rest of the day,” a fruit seller said, adding that some shop workers had been asked by government officials not to speak out about their accounts of the incident. President Xi Jinping ordered Xinjiang authorities to take "resolute measures" and crush "violent terrorists" after the attack in the restive Western region. Xinhua quoted local police as saying that knife-wielding assailants attacked people and set off explosives shortly after 7pm on Wednesday at the exit of the Urumqi South railway station. Four of the injured were in critical condition, Xinhua said. Two of those killed were suspected assailants who detonated explosive devices they were carrying, and the third was an innocent bystander, the official People's Daily said on Thursday. Watch: Several killed and dozens injured in Urumqi railway station attack Xi ordered Xinjiang officials to do everything in their power to help those injured in the attack, resolve the case quickly and mete out harsh punishment against the assailants, Xi said. More than 100 Uygurs were arrested after the attack, said a Uygur separatist group based in Germany. The Post has not been able to independently verify the alleged arrests. "The explosion in Urumqi proves that suppression is not a solution to the problem,” Dilxadi Rexiti, a spokesman for the World Uygur Congress, said in a written statement. “The Uygurs, who are struggling between despair and survival, hope Xi Jinping would give constructive suggestions to improve the chaotic situations with his visit to East Turkestan, but this has not happened,” Rexiti said, using the name preferred by Uygur separatists for the region of Xinjiang. The attack occurred just as Xi wrapped up his four-day inspection tour of Xinjiang. Xi had vowed to deploy a “strike first” strategy against terrorism to “deter enemies and inspire the people” during the tour, Xinhua reported. At a mosque in Urumqi on Wednesday morning, just two kilometres from the train station, Xi called on religious leaders to help followers to better understand religious teachings so people could live in peace. State television reported Xi was in Urumqi yesterday morning, meeting workers ahead of Labour Day today as well as local religious leaders. Police cordoned off all entrances to the station square and armed police were deployed, Xinhua added. Xinjiang government spokesman Luo Fuyong said the situation was “well under control” after the blast, according to Reuters. Hong Kong Travel Industry Council executive director Joseph Tung Yao-chung said he was not aware of any Hong Kong tour groups in Urumqi. A resident working at a nearby hostel told the South China Morning Post over the phone: “The blast was quite powerful and there were possibly deaths.” But another witness told the Post that "the bomb seemed home made, as the blast was not massive. Nobody had their limbs blown off." For years, resource rich and strategically located Xinjiang has been beset by violence that Beijing blames on Islamist militants and separatists. Li Wei, a Beijing-based counter-terrorism expert, said the blast showed that there were still weak links in security precautions. “Security checks at the exit of a railway station are more relaxed than at the entrance,” he said. Li said the terrorist attacks would not disappear soon even though the top leadership had highlighted the importance of tightening security. Additional reporting by Adrian Wan and Eddie Lee Tweets about "urumqi explosion"