"Tonight it appears that two snipers shot ten police officers from elevated positions during the protest / rally. Three officers are deceased, two are in surgery and three are in critical condition. An intensive search for suspects is currently underway. No suspects are in custody at this time."
Per Dallas police chief David Brown. Developing, I'll update this OP as we go.
Abundant video footage, since this happened in the middle (apparently?) of a Black Lives Matter protest downtown. I won't post any here, but that's just personal aesthetics.
Dallas PD have circulated a photo -- via twitter, because of course, this is reality now -- of a black man in a camo shirt and a rifle slung over his shoulder, apparently walking among other protesters in the daylight. One version of the shot showed it time-stamped on the original camera as July 7th.
Footage has also emerged of the same man standing with protesters and watching police - in what appears to be the immediate aftermath of shots fired elsewhere. Twitter users latched onto the footage and about an hour later Dallas PD were referring to the man as a person of interest rather than a suspect.
Initial footage/reports of a "suspect" in body armor being arrested was apparently confused; he was a protester making a fashion statement and is not considered a suspect.
Just a lot of rumor churn until 1 am; Dallas PD have announced the capture of two suspects in a Mercedes.
