A/HRC/18/21 international legal obligations. Some concrete examples have been cited to illustrate the findings, but these by no means constitute an exhaustive list. A. Extrajudicial killing and excessive use of force 32. Accounts and reports received by the Mission consistently alleged that Government security forces resorted to excessive use of force in response to peaceful demonstrators. The use of live ammunition, tear gas, batons, electronic stun guns and polluted water cannons has been documented. Gunmen in uniform or plain clothes were seen on buildings or at street level allegedly in order to target protesters marching to or protesting outside public buildings with live ammunition. The police reportedly stood by on many occasions while unarmed protesters were attacked or shot at by armed men in plain clothes. 33. It appears that once peaceful demonstrators began to march from their sit-ins to protest outside public buildings, tensions rose sharply. Security forces, fearing that the buildings might be attacked and ransacked, often fired on demonstrators; in some cases individuals were apparently targeted and shot. 34. Based on accounts and casualty figures made available to the Mission, by February 2011, a pattern of use of live ammunition to quell protests had emerged in Aden, which is consistent with security forces responses against demonstrations organized by Al-Harak in past years. Subsequently, Sana’a, Ta’izz, Ibb, Al-Hudaydah, Al-Mukalla, Dhamar, AlBayda and other localities experienced similar violence, at different levels. The Mission did not receive information regarding systematic investigations into the excessive use of force by security forces. 35. The Mission received accounts regarding cases of extrajudicial and summary executions in the course of demonstrations: Gyab Ali Al-Saadi, the son of a leading member of the Peaceful Southern Movement, was reportedly targeted and shot in the chest in Aden on 24 June 2011, while attempting to persuade soldiers, backed by tanks, not to fire on persons attending the funeral of Ahmed Al-Darwish. Also, according to allegations, the vehicle of General Ali Mohsen Al-Ahmar was shot at by unidentified men in military uniforms, after he defected with his unit, the first armoured division, but he was not harmed. In addition, teacher and student demonstrations, calling respectively for increased salaries and the postponement of exams, apparently turned violent in Ta’izz when Central Security Forces attacked the protestors, reportedly killing one student. The Mission was further informed by several sources about mass graves of victims of extrajudicial executions allegedly committed by Government affiliates in the context of the repression in Sana’a and Ta’izz. However, the Mission did not receive any evidence to substantiate these allegations. 36. The Mission was briefed extensively on the events of 18 March 2011 in Sana’a and 29 May 2011 in Ta’izz. The details of the events on those days are highly contested, in particular with respect to the perpetrators and the number of victims. Some interlocutors and documents asserted that more than 50 people were killed on each of those days. It was brought to the attention of the Mission that many victims and/or their families refuse to cooperate with investigations launched by Government institutions, since they no longer consider such institutions impartial or even legitimate. The Mission is aware that 78 persons are on trial in relation to the 18 March 2011 events in Sana’a, and that investigation of the 29 May 2011 events in Ta’izz is ongoing. The Government did not provide information on how many of the 78 persons charged for the events in Sana’a belong to security organs. 37. On the other hand, in statements made to the Mission, the Government stressed that the security forces had orders from President Saleh to exert restraint and use firearms only 9