 I am told by law enforcement sources that the online environment is awash in calls for violence, conspiracy theories. I have worked, unfortunately, far too many mass shootings. There are often calls for retaliatory violence and copycat attacks. JOHN YANG, The Republican National Convention is set to get under way tomorrow in Milwaukee. CBS' Natalie Brand is there. AMNA NAWAZ, RNC delegates and volunteers shocked by the shooting say they will carry on. How do you think the tone will change this week?