|The Dallas Police Department said this man was wanted over the shooting|
The protest was drawing to an end when shots rang out near the area of Market and Main streets in downtown Dallas just before 9pm on Thursday, local time.
Dallas Police chief David Brown said it appeared four suspects had worked together to fire from elevated positions during the protest, shooting 11 Dallas police officers.
Four of those officers were killed, two were in surgery, and three were in a critical condition. Dallas Police Department tweeted out a fifth officer died early Friday.
He said the snipers fired upon the officers "ambush-style", with some shot in the back in a bid to kill as many as possible.
"We believe that these suspects were positioning themselves in a way to triangulate on these officers ... and planned to injure and kill as many law enforcement officers as they could," he said.
Several hours after the shooting, three suspects were in custody while one remained in negotiations with police from the garage of El Centro College in Main Street, after shooting at them for 45 minutes.
Two of the suspects were arrested after they were seen to throw a camouflaged bag into the back of a black Mercedes before speeding from the scene of the shooting. Another suspect, a woman, was arrested near to El Centro College.
The suspect told negotiating police that "the end is coming" and he was going to "hurt and kill more of us, meaning law enforcements", Brown said. The suspect also said there were bombs "all over the place" across downtown Dallas.
"We are being very careful in our tactics... as we negotiate further," Brown said in a press conference at 12.40am on Friday, local time.
"We still don't have a complete comfort level that we have all the suspects... we're likely to be working throughout the early morning hours of Friday until we're satisfied that all suspects have been captured."
Earlier, the Dallas Police Department released an image of a "person of interest" who was wanted over the shooting, pictured wearing a camouflage t-shirt. However, it is not believed this man was involved in the shooting.
Dallas Area Rapid Transit (DART) said one of its police officers was among the dead, and three other of its officers who were shot had injuries that were not life-threatening.
The protest was being held following the deaths of two men - Alton Sterling in Louisiana, and Philando Castile in Minnesota - in separate police shootings this week. The men, who were both black, were killed by police officers, and their deaths were captured on mobile phone cameras.
One witness at the protest in Dallas told Fox News that "complete pandemonium" broke out when shots were fired towards the end of the rally.
"Everyone just took off running," he said.
He believed the shooter had an assault rifle, and said police returned fire.
The shooting unfolded near one of the busiest parts of the city's downtown.
Footage of the panic in the moments immediately after the shooting circulated widely on social media. In many of the videos, multiple gunshots could be heard ringing out, while teams of police officers could be seen running through the area.
"There's no indication of who the suspects are or what their motives were, except they fired on the police," said Clay Jenkins, the Dallas County judge and the county's chief executive.
"We are still seeking a suspect that may be held up at a downtown building, so we're asking the public to stay away. All government buildings in that area are on lockdown. That's the government centre where this is happening."
The Dallas Police Department's Twitter account had been tracking the protest's progress through the city, but abruptly stopped tweeting about 9pm, local time.
CBS news anchor Doug Dunbar tweeted that a witness reported hearing "about 20 shots in succession".
Dozens of officers were at the scene "with their guns drawn", Dunbar said.
Another witness, Michael Bautista, said he saw one police officer on the ground as he fled the scene.
"I saw the bullets hitting the cop cars," he said.
He said the protesters had been involved in a "peaceful march" before the shooting occurred.
Devante Odom, 21, told The Dallas Morning News that everyone "just started running" when the shots were fired. "We lost touch with two of our friends just trying to get out of there," Devante said.
Renee Sifflet of Dallas stood at the corner of Commerce and Houston, waiting for the chaos to die down so she could retrieve her three teenage children, who were in hiding.
"I brought them here for a positive experience, something they could say they were part of when they're older," she said. "Then it turned negative."
When they started running, she said, she lost track of her 15-year-old son for two minutes in the mayhem. "Thank God he has a cellphone," she said.
Carlos Harris, who lives downtown, said the shooters "were strategic. It was tap tap pause. Tap tap pause."
Harris, who said he was in the military, said he heard someone fire back with an AR-15.
Before the shots were fired, the demonstrators were peacefully walking down Main Street.
"The cops were peaceful," he said. "They were taking pictures with us and everything."