Gunman at Trump rally tentatively identified, FBI says

Law enforcement officials held a press conference after deadly gunfire erupted at a Trump campaign rally in Butler, Pennsylvania. Subscribe to ABC News on YouTube: ABC News Digital is your daily source of breaking national and world news, exclusive interviews and 24/7 live streaming coverage. Download the ABC News app for the latest headlines and alerts: Watch 24/7 coverage of breaking news and live events on ABC News Live: Watch full episodes of World News Tonight with David Muir here: Read ABC News reports online: ABC News is the home to the #1 evening newscast “World News Tonight” with David Muir, “Good Morning America,” “20/20,” “Nightline,” “This Week” with George Stephanopoulos, “ABC News Live Prime” with Linsey D