MYANMAR security forces opened fire on protests against military rule yesterday, killing at least 13 people, witnesses and media reported, a day after neighbouring countries called for restraint and offered to help Myanmar resolve the crisis. The security forces resorted to live fire with little warning in several towns and cities, witnesses said, as the junta appeared more determined than ever to stamp out protests against the February 1 coup that ousted the elected government of Aung San Suu Kyi. "It's horrific, it's a massacre. No words can describe the situation and our feelings," youth activist Thinzar Shunlei Yi told…