( CNN ) -- Live ammunition fired by Yemeni security forces left 11 protesters dead in Sanaa and Taiz on Wednesday , witnesses said , as a human rights group called for an end to the use of deadly force by government troops . Doctors and eyewitnesses in the cities told CNN that another 169 people had been injured , some critically . `` Shots are heard everywhere in Sanaa , '' a witness told CNN . Journalists and medical sources said eight people were killed in the capital when Republican guards began shooting directly at demonstrators in the eastern and northern parts of Change Square . At least 65 people were injured , the sources said , 12 critically . They added that more than 100 additional people suffered injuries from rocks or batons . `` Security forces are aiming for a massacre in Sanaa , '' said Abdul Wahab Anesi , a medical staff spokesman at a field hospital set up in Change Square . Before Republican Guards began firing at protesters in the square , they reportedly clashed with military personnel who had been protecting demonstrators gathered there . Journalists , medical sources and other witnesses told CNN that these soldiers defected two months ago along with Maj. Gen. Ali Mohsen Al-Ahmar , who withdrew his support from President Ali Abdullah Saleh in late March . At the time , he promised to protect civilians demonstrating against the president . In addition to the casualties in the capital , three people were killed and four were reported critically injured in Taiz . `` The attack took place while we were chanting , 'One more week left for you , Saleh , ' '' said Sabir Ali , a protester in Taiz . The protesters were giving Saleh a week to step down , saying if he does not , they will make good on a vow to march to the presidential palace . Earlier , a senior security official denied that forces fired on protesters in Taiz . `` Security forces were preventing attacks on civilians led by gangs of the opposition , '' the official said . `` Security forces did not shoot at protesters . Gangs of the JMP were the shooters . '' The JMP stands for the joint meeting parties , a coalition of opposition parties . `` Security forces kill people , then deny the incident , '' said Ahmad Bahri , head of the political office at the opposition Haq party . `` This is why the Yemeni revolution is taking place . '' He said the protesters were unarmed and were marching peacefully when they were shot . Those who died were shot in the head , Bahri said . Civil disobedience was also seen in the cities of Abyan , Aden , Ibb , Hodeida and Amran , according to reports . Amnesty International , in a release Wednesday , again called on Yemen 's government to stop the use of deadly force against anti-government protesters . `` Security forces in Yemen must be immediately stopped from using live ammunition on unarmed protesters , '' said Philip Luther , Amnesty International 's deputy director for the Middle East and North Africa . `` The Yemeni government must allow its people to express their genuine grievances without fear of violence and killing . It must also ensure that justice is done for all those killed unlawfully while exercising their right to peaceful protest . '' The high representative of the European Union for foreign affairs and security policy , Catherine Ashton , echoed that call in a statement released Wednesday . `` I am following with the utmost concern the developments in Yemen , '' Ashton said . `` I condemn in the strongest terms the ongoing violence and repression against protesters in Sanaa , Taiz and other cities . I call on the government and security forces to end the use of violence immediately . '' Ashton urged Yemeni groups to sign a political transition agreement worked out by the Gulf Cooperation Council , and to implement it without delay . The agreement stipulates that Saleh transfer power and leave office within 30 days of signing the deal . It also provides immunity for him and those who served in his regime and calls for a unity government to be formed within seven days . Protesters calling themselves Revolution Youth had called for a civil disobedience day on Wednesday . More than 95 % of the shops in Taiz were closed , according to witnesses . On Monday , medical officials said at least six people were killed and hundreds were wounded when teachers , accompanied by opponents of Saleh 's government , demonstrated against salary cuts . Witnesses said security forces fired on the protesters after dispersing marchers with batons and tear gas . CNN can not independently verify the witnesses ' accounts . Saleh 's impoverished and unstable nation has been wracked by anti-government protests and clashes between demonstrators and security forces for many weeks .
Live ammunition is used against protesters in Sanaa and Aden , they say . At least 169 people are injured by bullets , grenades or batons in both cities , they say . The Republican Guard fought military personnel who were protecting demonstrators . The soldiers were unarmed , according to an opposition security official .