Officials have no information about whether anyone was inside the RV when it exploded. Police also tweeted a photo of the RV as it was driven into the area at 1:22 a.m. Friday. As the investigation continues, officials will meticulously search the area for any trace of physical evidence, according to Andrew McCabe, a CNN law enforcement analyst and former FBI deputy director. Essential pieces of evidence, however, could be scattered across a large scene, given the size of the blast. The most important question to answer at this time is who was behind the blast, McCabe said. "We need...