A visibly frustrated President Obama offered condolences to the victims of the mass shooting at an Oregon college on Thursday, but he added that "our thoughts and prayers are not enough" to stem an epidemic of mass shootings in the United States. Having now spoken after 15 such senseless killings during his administration, Obama again called for "common sense" legislation aimed at preventing gun violence, and he mocked opponents of past initiatives he has pushed. "Each time this happens, I'm going to bring this up," Obama said during emotional remarks in the White House press room. Obama said he has...