Police in Urumqi shot dead two Uygurs and wounded a third yesterday, inflicting a major blow to the fragile peace that has settled on the riot-torn city. The incident - the first confirmed clash since a riot police officer was stabbed on Friday - brought a heavy police response, with hundreds of riot police and soldiers blocking off streets and effectively closing off a largely Uygur-inhabited district. It was also the first time the government admitted to shooting anyone since the ethnic unrest erupted on July 5, despite claims to the contrary by exiled Uygur groups. An official statement released last night said three Uygur suspects were attacking a fourth with long knives and wooden clubs at 2.55pm. The police on patrol tried to stop the fight, but encountered resistance. 'The police fired warning shots before shooting at the three suspects,' it said. The official statement apparently contradicted witness accounts, which indicated that clashes had occurred involving both Uygur and Han Chinese. One person told the South China Morning Post that he had seen four injured Han Chinese civilians. However, the man, who refused to give his name, said he had not seen how the four had sustained their wounds. The Associated Press, meanwhile, reported that armed police chased a man of Uygur appearance and kicked and beat him with batons. Gunfire was heard before and during the incident near one of the city's main Uygur neighbourhoods, but it was not clear if they were connected, or whether the incident was connected to the Uygur deaths. The official account did not mention any wounding of police officers, despite the fact Hong Kong journalists saw ambulance workers tending to a riot police officer who was bleeding profusely from an abdominal wound. Nor did it refer to a hospital siege by security forces that was witnessed by hundreds of onlookers, or the massive security operation following the incident. Security forces armed with semi-automatic rifles and supported by armoured personnel carriers lay siege to the unfinished wing of a maternity hospital where witnesses said one unarmed suspect had taken refuge. 'I saw one Uygur being chased by police. He ran into the building to hide,' said a Uygur onlooker who identified himself as Anwar. 'The man didn't look armed. He had nothing in his hands.' A Post reporter was removed from the scene as police moved to clear the entire area of journalists just as staff were being taken away from the hospital building before the siege was resolved. Reporters were told the action was due to safety concerns, but large crowds of both Han and Uygur onlookers were allowed to remain. 'I cannot allow you to interview Uygurs on the street in case you are attacked,' a police officer told the Post. Despite the uneasy stability brought by the estimated 10,000 troops and riot police on the streets of the Xinjiang capital, ethnic tensions remain close to breaking point. Yesterday's violence adds weight to rumours that sporadic clashes have been going on throughout the past week. Zhou Yongkang, the nation's top security official, said that while the situation was improving, the government could not rest on its laurels. 'Currently, various instability factors still exist and the task of maintaining stability is arduous,' he said.