China's president has urged "decisive actions" against "terrorist attacks" in Xinjiang after a deadly blast at a railway station, state media say.
The explosion took place on Wednesday as President Xi Jinping completed a tour of the region.
Three people were killed and 79 injured when attackers used knives and detonated explosives at Urumqi's south railway station, officials said.
They say they now believe two of the attackers were among the dead.
The Xinjiang government news website said the pair had come under the influence of "extremist religious thought and participated in extremist religious activities".
The far western province has seen a series of violent attacks in the past year.
Beijing has blamed such violence on separatists from the mainly Muslim Uighur minority.
This incident follows an attack on Kunming station, in southern China, in March - also blamed on Uighurs - in which 29 people died.
Mr Xi's visit to the western Xinjiang region was the first since he became president in 2012.
"The battle to combat violence and terrorism will not allow even a moment of slackness, and decisive actions must be taken to resolutely suppress the terrorists' rampant momentum," Xinhua news agency quoted him as saying after the attack.
Mr Xi said it was essential to "deeply understand Xinjiang separatism".
Xinjiang's local government news portal said the attack began with an explosion at an exit of Urumqi South Station at around 19:10 as the train from Chengdu arrived.
"According to initial police investigations... the attackers used knives to stab people at the station exit, and detonated explosives at the same time," it said, adding that all the injured were receiving medical treatment.
Witnesses told Xinhua news agency that the explosion appeared to be centred around luggage left on the ground between a station exit and a bus stop.
However, several microblog posts and photos related to the explosion appeared to have been quickly deleted from Sina Weibo, China's largest microblog platform.
The local government described it as a "violent terrorist attack".
The station has now reopened.
The launch of three new inter-city railway lines linking Urumqi with three other cities in Xinjiang had been scheduled for Thursday, Xinhua said.
The attack came at a peak travel time as passengers embarked on the getaway ahead of China's Labour Day holiday on Thursday.
Earlier in his four-day trip to Xinjiang, Mr Xi vowed to deploy a "strike-first approach against terrorists in the region", according to Xinhua, saying the region's long-term stability was "vital to the whole country's reform".
Xinjiang has witnessed serious ethnic tensions in recent years, including ethnic riots in Urumqi in 2009 that left about 200 people dead.
The region's Uighur Muslim minority, who number about nine million, have long complained of political, religious and cultural repression under Chinese rule. Beijing rejects this, saying it has poured money into the region to develop it.
In March, Chinese officials blamed Uighur separatists for the mass knife attack in Kunming. Almost 150 people were hurt, as well as the 29 who died in an incident that shocked China.
They also blamed an incident in Tiananmen Square last year in which a car ploughed into a crowd on Uighurs inspired by Islamic extremists.
"We have seen attacks and problems in Urumqi before, but we haven't seen anything on this scale in quite a while," said Raffaello Pantucci, a senior research fellow with the military think-tank the Royal United Services Institute.
"I think the issue is that the problem [of attacks] in Xinjiang is getting worse," he told the BBC, adding that he believed incidents were becoming more professional and aimed at larger targets.