Most recent update:
All shooting was done by one suspect, the one captured on the video from the hotel across the street. He was cornered by police where he made statements about wanting to kill white people, especially police, and was motivated by the recent police shootings. He had an explosive device with him and the police chose to detonate it rather than risk the safety of the public. Suspect was killed in the explosion.
If the above is correct, it's another example of what damage one individual can do. Up til this report, it was believe multiple shooters were involved, all shooting from elevated positions. None of that early speculation turned out to be correct, apparently.
Three other suspects in custody, so this story has more to it.
http://abcnews.go.com/US/dallas-shooting-suspect-wanted-kill-white-people-white/story?id=40431306