 This must stop. The American people can rest assured that we will leave no stone unturned as we work to get to the bottom of what happened yesterday. The FBI said it believes Crooks, who had bomb-making materials in the car he drove to the rally, acted alone. Investigators have found no threatening comments on social media accounts or ideological positions that could help explain what led him to target Trump before the Secret Service rushed the presumptive Republican presidential nominee off the stage.