Now Playing: Facebook Hits 500 Million Members

Now Playing: Mark Zuckerberg

Now Playing: Zuckerberg Says No Contract Was Signed

Now Playing: Trump, upset about Russia probe, meets with deputy AG and FBI director

Now Playing: Officers engaged in firefight with accused shooter inside school: Police

Now Playing: Urgent manhunt for 2 escaped inmates charged with murder

Now Playing: The 3 moments of the royal wedding that everyone is still talking about

Now Playing: Meghan Markle's official biography posted to the royal family's website

Now Playing: Georgetown athlete walks for 1st time since suffering spinal-cord injury

Now Playing: Officer responding to call about suspicious vehicle killed: Police

Now Playing: DNA tests underway to confirm captured cougar attacked bikers

Now Playing: Woman says she was stopped, questioned by Border Patrol after speaking Spanish

Now Playing: NYPD investigating chef in connection with 2 sexual assault allegations: Sources

Now Playing: 1 man dead, 1 injured after mountain lion attack

Now Playing: The first lava flows from Kilauea reaching Pacific

Now Playing: Man accused of driving his own car through his own restaurant

Now Playing: Couple get married in torrential rain

Now Playing: Woman killed in mudslide in North Carolina

Now Playing: Trump to 'look into' whether campaign was 'infiltrated'

Now Playing: Foreign exchange student killed in school shooting mourned