According to this AFP report three men disrupted prayer service, attacked  an unarmed police inside the mosque, before they were shot by armed police outside the mosque. Two died one injured:

http://www.straitstimes.com/Breaking%2BNews/Asia/Story/STIStory_402959.html/

BEIJING – THREE Uighur men tried to incite other Muslims to launch a ‘jihad’ and attacked a mosque security guard before police shot and killed two of them, state media reported on Tuesday.

The incident began when around 150 Muslims were praying in a mosque in Urumqi, the capital of the northwest Xinjiang region on Monday, Xinhua news agency said, citing an unnamed imam who was giving a service at the time.

One man stood up and tried to take over the prayers but was stopped, the imam told Xinhua. A few minutes later the man reportedly stood up holding a green banner and started calling for a ‘jihad’.

The imam then ended the prayers, adding: ‘We will definitely not follow you. Get out!”, according to Xinhua.

As the man was being ordered from the mosque, two other men took out three 50 centimetre long knives from a bag, Xinhua said.

Security guards then tried to stop the men. One of the guards, aged in his 40s who did not want to give his name, said the group chased him out of the mosque wielding the knives where they met patrolling police, Xinhua said.

Police fired warnings shots to try to stop the men before shooting at the three, killing two and injuring one.

A government statement released on Monday soon after the attack said: ‘Police shot and killed two suspected lawbreakers and injured one suspected lawbreaker using legal means.’ The statement said the three Uighurs were trying to attack another person from the Uighur minority group.

The government’s statement and the Xinhua report conflicted with accounts by two Uighurs who said they witnessed the incident from 50 metres away and that three Uighur men had been trying to attack security forces. ‘They hacked at the soldiers with big knives and then they were shot,’ said one of the witnesses, who said the incident took place across the street from a mosque.

The incident showed the city remained volatile despite a huge security clampdown following unrest on July 5 which left more than 180 people dead, in the worst ethnic violence to hit the country in decades. Thousands of Han Chinese retaliated in the following days, arming themselves with makeshift weapons. Despite a hefty security presence, authorities have since struggled to keep a lid on sporadic violence. — AFP