A review by The Associated Press shows the shooting was sparked by a belligerent political clash between a large group of white Trump supporters and four unarmed Black girls all aged 16 and under.
Experts in homegrown extremism have warned for years about efforts by far-right militants and white-supremacist groups to radicalize and recruit people with military and law enforcement training.
Director Christopher Wray said the FBI remains concerned about the potential for violence at protests and rallies in Washington and in state capitols around the country.