A scruffy, malodorous, apparently homeless male of indeterminate race was seen hobbling from the scene. Secret Service and local police have released this surveillance photo of the suspect and ask for the public's cooperation in locating the suspect.
Newsflash- Small pea-sized round object thrown at POTUS motorcade
http://www.orangejuiceblog.com/wp-content/uploads/2016/02/angry-homeless-1.jpg
"You only have power over people so long as you don't take everything away from them." Solzhenitsyn