Five police officers were fatally shot and seven others wounded Thursday when snipers opened fire in downtown Dallas during a protest over recent police shootings in Minnesota and Louisiana, police said.
Three possible suspects were in custody, and police were locked for several hours in a standoff with a gunman in a parking garage who had fired at officers, Dallas Police Chief David Brown said.
The suspect told officials there were "bombs all over the place in this garage and downtown," and "told our negotiators that the end is coming, and he's going to hurt and kill more of us," Brown said.
The standoff ended at about 2:30 a.m., according to Dallas city spokeswoman Sana Syed, but she would not confirm reports that the gunman was dead. Two hours later, Dallas Mayor Mike Rawlings said the suspect in the standoff had died.
Three officers remained in critical condition, Syed said.
Speaking Friday from a NATO summit in Warsaw, President Obama said the Dallas shooters had "twisted motives" and that the attack was without any justification.
"We still don't know all the facts. What we do know is that there has been a vicious, calculated and despicable attack on law enforcement," Obama said. He called on the U.S. to support police and the victims.
"Today is a wrenching reminder of the sacrifices that [law enforcement officers] make for us," he said, adding: "The entire city of Dallas is grieving. Police across America -- which is a tight-knit family -- feel this loss to their core. "
The shooting interrupted what had been a peaceful march of about 800 people through downtown Dallas to protest recent police shootings of black men in Baton Rouge, La., and in a suburb of Minneapolis. Several other U.S. cities held similar demonstrations Thursday, and about 100 police officers were on the scene in Dallas when gunfire broke out.
"We believe that these suspects were positioning themselves in a way to triangulate on these officers from two different perches and garages in the downtown area and planned to injure and kill as many law enforcement officers as they could," the chief said.
Police throughout the evening were looking at a variety of "persons of interest."
One man seen wearing camouflage and carrying a rifle, identified as a "person of interest" in a police photo disseminated to the public, quickly turned himself in, police said. A relative said the man was a protester, not one of the gunmen, and he was later released, according to Dallas media.
One person was seen carrying a camouflage bag and walking quickly down Lamar Street, then throwing the bag into the back of a black Mercedes and driving off at a high rate of speed, Brown said.
Officers pulled the vehicle over and took its two occupants into custody.
Another suspect, a female, was also taken into custody, Brown said.
In a video shot from the perspective of a demonstrator seconds before the shooting, a crowd of protesters walks forward chanting, "Hands up, don't shoot!" a phrase popularized after the death of Michael Brown in Ferguson, Mo., in 2014.
Ten seconds later, the camera suddenly lowers as bodies scatter and the shooting begins. "Go, go, go … run, run, run!" a woman shrieks. "Someone's shot! There was a gun.… Someone got shot! Someone got shot!"
An eyewitness video that aired on KDFW-TV appears to show a gunman outflanking and shooting a police officer.
The footage shows a man with a rifle standing on the sidewalk, hiding behind a pillar. As another person, apparently a police officer, approaches from behind and hides behind a separate pillar, the gunman turns around and runs toward the officer's pillar, then apparently shoots the officer in the back at close range.
The officer fell to the ground.
At least four of the officers belonged to the Dallas Area Rapid Transit agency, including one of those who died, according to the agency's Twitter account.
"Our thoughts and prayers are with the Dallas law enforcement community and the Dallas Area Rapid Transit (DART) officers killed and injured this evening," Texas Gov. Greg Abbott said in a statement.
"In times like this, we must remember — and emphasize — the importance of uniting as Americans," he said.
The protest began at Belo Garden Park, across from Bank of America Plaza in the center of downtown Dallas.
"Enough is enough," demonstrators shouted, holding signs that said, "If all lives matter, why are black ones taken so easily?"
Larissa Puro, a 26-year-old University of Southern California communications manager who was on vacation in Dallas for a family reunion, was holed up in the kitchen of the nearby Omni hotel while the police manhunt was underway.
"We couldn't enter our hotel, and … police told us to run into the hotel kitchen and said there had been a shooting," Puro said.
"People were crying," she said. "I feel so awful for all the police officers out there."
Videos posted throughout the evening to Twitter and Facebook showed protesters and observers in a frantic commotion as police sirens blazed downtown.
In one video posted to Facebook, Michael Kevin Bautista was standing across the street from four police cars a block from Belo Garden Park.
"They are shooting now, there's an officer down," Bautista says into the camera. "They're moving in on somebody. I think they might have gotten somebody."
Later, police rush by him, saying, "Get out of here! Get out of here!"
Wyatt Rosser, a 20-year-old from Dallas who had come to the demonstration, said the shooting did not represent the peaceful demonstrators who had assembled.
"These shooters were radicals. The overall message of today's demonstration was strength, solidarity and peaceful action. It was actually the most peaceful Black Lives Matter demonstration I'd been to," he said.
"Nothing that the speakers, or anyone, spoke about tonight in any way encouraged or supported the actions of these shooters. And it is saddening that all of that is overshadowed by their violent actions," he said.
The Dallas shootings were not the only place where protests led to trouble. In Portland, Ore., where protesters gathered downtown outside the county justice center, police tweeted that they arrested a man who was "displaying a gun during a demonstration."
No shots were fired. Tweets from a reporter for CBS affiliate KOIN said that "everyone ran screaming." A video of the man purported to have the gun quoted him as saying he pulled it out because he feared for his life in the crowd. The reporter said the man was quickly and "aggressively taken down by police."