Large groups of police armed with semi-automatic weapons and batons were deployed close to the scene of Monday’s violence, where Chinese authorities said police shot and killed two Uighur “lawbreakers” and wounded another.An Algerian-based Al-Qaeda affiliate was meanwhile calling for reprisals against Chinese workers in northern Africa, according to an intelligence report by London-based risk analysis firm Stirling Assynt.Heavily armed security forces were out in force in China’s volatile Urumqi on Tuesday close to where police shot dead two Muslim Uighurs who state media said were calling for jihad.The latest shooting was the first time the government said security forces had killed anyone since the unrest broke out, despite claims by exiled Uighurs that many people had died in the clampdown.Thousands of Han Chinese retaliated in the following days, arming themselves with makeshift weapons and marching through parts of Urumqi vowing vengeance against the Uighurs.An online petition signed by a number of Chinese writers and democracy activists is calling for the release of a Uighur activist in Beijing who disappeared during last week’s clashes in Urumqi, as both the Chinese government and Uighur supporters battle to make their case in the public realm.