I agents on Saturday raided a Riverside home belonging to a friend of San Bernardino shooter Syed Rizwan Farook as they try to determine whether the man purchased two of the semiautomatic rifles used in the massacre, according to a law enforcement source. The source, who asked to remain anonymous because the case is ongoing, said officials have been trying to talk to man to see what he knows about the attack. It's far from clear whether the man had anything to do with the violence or even knew what Farook did with the guns, the source added. A second...