The Texas gunman who murdered 19 children and two teachers posted an online message warning that he was going to shoot up an elementary school minutes before he attacked, Governor Greg Abbott said on Wednesday, as more harrowing details about Tuesday's rampage emerged. The gunman, 18-year-old Salvador Ramos, also sent a message on Tuesday saying he was going to shoot his grandmother and another one confirming he had done so, Abbott said at a news conference. Ramos' grandmother, whom the suspect shot in the face shortly before attacking the school, survived and called...