DALLAS • It began peacefully. For two hours, roughly 800 people marched, chanting and waiving signs to protest against recent police shootings of black men in the United States.
But as dusk settled over Dallas on Thursday, bullets suddenly began flying, the crack of high-powered ammunition cannoning off skyscrapers and across the downtown area. Terrified protesters scattered in all directions as startled police officers, who had been guarding the march, gazed up in search of the origin of the shots.
"I didn't see anybody else get shot, just the cops. I saw cops getting shot, right there in plain sight," said witness Cortney Washington.
Another witness, Mr Lynn Mays, recounted the moment when the shooting began: "All of a sudden, we started hearing gunshots out of nowhere. At first, we couldn't identify it because we were not expecting it, then we started hearing more, rapid fire. One police officer who was standing there pushed me out of the way because it was coming in our direction… next thing you know, we heard 'Officer down'."
The shootings occurred only a few blocks from Dealey Plaza, where President John F. Kennedy was assassinated in 1963.
Protest organiser Cory Hughes told CNN: "There were blacks, whites, Latinos, everybody. There was a mixed community here protesting. And this just came out of nowhere... It was complete pandemonium."
While most protesters ran for cover, a few turned their cameras from the demonstration to the chaos unfolding around them. In perhaps the most shocking footage to emerge on the horrific and highly televised night, a gunman was seen sneaking up behind a police officer and shooting the cop several times in the back at point-blank range. It is unclear if the officer survived.
"It looked like an execution, honestly," Mr Ismael DeJesus, who took the video from an apartment building, told CNN.
Videos taken by bystanders also showed officers dragging fallen comrades out of the line of fire.
Some showed officers choking back tears for their fallen colleagues. One officer appeared to brace himself against his vehicle as grief overcame him.
Officials said a total of five police officers were killed by at least one sniper. Two civilians were also injured. One suspect, who was involved in a three-hour stand-off with police, was killed while three other suspects were in custody.
Dallas Mayor Mike Rawlings said it was "a heartbreaking morning" and called for unity. "We as a city, we as a country, must come together and lock arms and heal the wounds we all feel," he said.
Outside the city's Parkland Hospital, police saluted their fellow officers who lost their lives or were wounded in the shooting. Other people later joined the officers for an impromptu vigil.
Presidential candidates, Republican Donald Trump and Democrat Hillary Clinton, cancelled planned events following the attack.
"This is a time, perhaps more than ever, for strong leadership, love and compassion. We will pull through these tragedies," Mr Trump said in a statement.
Mrs Clinton said on Twitter: "I mourn for the officers shot while doing their sacred duty to protect peaceful protesters, for their families and all who serve with them."
WASHINGTON POST, REUTERS, AGENCE FRANCE-PRESSE