Now Playing: Crowds clash during Boston march after free speech rally

Now Playing: Thousands march through Boston week after Virginia bloodshed

Now Playing: The signs held up by the counterprotesters

Now Playing: Two officers shot in Kissimmee, Florida

Now Playing: Boston braces for possible violence at 'free speech rally'

Now Playing: Family of American killed in Spain terror attack speaks out

Now Playing: White nationalists, counterprotesters face off in Kentucky

Now Playing: Violence erupts between white nationalists, counterprotestors in Charlottesville

Now Playing: White nationalists Matthew Heimbach, Richard Spencer on their controversial beliefs

Now Playing: White nationalists, counterprotesters prepare for Kentucky rally

Now Playing: Who are the white nationalists and Antifa

Now Playing: White nationalist Richard Spencer, Antifa member Lacy MacAuley confront each other

Now Playing: Mother of Heather Heyer 'won't talk to Trump'

Now Playing: Father and daughter kicked off a Frontier flight

Now Playing: 3 girls found dead in Maryland

Now Playing: Two sisters to work with NASA during solar eclipse

Now Playing: Sneak peek: the new 'Uncharted' video game

Now Playing: 'Real Live': Late-night show hosts get real about Charlottesville protests

Now Playing: 'Real Live': The total solar eclipse

Now Playing: Steve Bannon out as White House drama continues