In Yemen, at least 16 people have been killed in a government assault on protesters in the capital Sanaa. Witnesses said the demonstrators came under attack in the capital's Change Square – the focus of the protests. The attack on the camp's southern end reportedly started late Friday. A medic at the field hospital in the square said 55 were wounded in the attack, in which government forces had used armoured vehicles and rifles. Other reports spoke of government troops shelling the 4 kilometers stretch of avenue. Earlier yesterday, at least 13 people reportedly died in fighting in the capital.The violence comes after President Ali Abdullah Saleh returned from Saudi Arabia three months after surviving an assassination attempt. After his surprise return to Sanaa, President Saleh called for a ceasefire to stop violence which has already claimed about 100 lives this week, mainly of unarmed anti-government protesters. He was quoted by the state news agency Saba as saying he was carrying the dove of peace and an olive branch.