Warning issued for large Fourth of July celebrations

ABC News senior investigative correspondent Aaron Katersky describes what law enforcement is doing to prepare for potential threats and which cities may be “attractive targets.” 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 Ste