US President Barack Obama on Thursday decried the \"outrageous bloodshed\" in Syria as government forces launched a deadly blitz on the protest city of Homs. Government troops trying to crush opponents of President Bashar al-Assad have killed at least 400 people in a relentless six-day onslaught on Homs, opposition activists say. Rights groups estimate that more than 6,000 people have died in the nationwide crackdown since mid-March.