WATCH: Witnesses Post Videos of Chaos Erupting at Dallas Protest

UPDATE, 11:20am ET: The Associated Press is identifying the gunman who murdered 5 Dallas police officers Thursday night as Micah Johnson, 25. Read more, here.

UPDATE, 8:45am ET: The Dallas police chief said moments ago that the suspect in the ambush on police officers was killed using an explosive device detonated by a robot.

He said the suspect was cornered. During negotiations, the man expressed that he was "upset about Black Lives Matter" and wanted to kill white people, especially police officers.

Watch the latest above and read more here.

Five Dallas police officers were killed and at least six more injured in a coordinated sniper attack during an anti-police brutality protest Thursday, an explosion of violence that President Obama declared a “vicious, calculated and despicable attack on law enforcement.”

Three people were in custody and one suspect dead as local police and federal authorities raced to determine a motive and whether more people were involved in what was the nation's deadliest day for police since 9/11. The suspects were not cooperating, officials said. Law enforcement veterans told Fox News the attack was clearly coordinated and showed an alarming degree of planning and sophistication.

Read more at FoxNews.com.

Casey Stegall reported on Fox and Friends that 12 officers were shot, with five dead. All of the deceased officers were male, he said.

1:40a - Dallas Police Chief David Brown said at a news conference that police are currently in negotiations with a shooting suspect in the garage of El Centro in downtown Dallas.

Brown said the suspect has been exchanging gunfire with police over the past 45 minutes and was not being very cooperative in negotiations.

He said plans were being worked up to end the standoff.

Brown said the suspect has told negotiators that "the end is coming, and he's going to hurt and kill more of us -- meaning law enforcement -- and that there are bombs all over the place in this garage and in downtown."

Brown said police would be very careful not to injure or put any officers or citizens in harm's way. He said that officers would continue working through the morning until all suspects have been captured.

Brown also revealed that a female suspect was apprehended in the same area of the garage, and that two other suspects in a Mercedes with camouflage bags were arrested and being interviewed.

Mayor Mike Rawlings said a section of downtown Dallas would continue to be an active crime scene in the morning "and we are determining now how big that crime scene is."

He said people who work downtown should check dallascitynews.net to see what areas to stay away from.

Watch the presser above.

1:02a - Shepard Smith reported that the threat to the public appears to be over as both suspects are now in custody.

Police bomb squad personnel, meanwhile, were working to neutralize a "suspicious package'" found at a downtown location.

Multiple police officers were fatally shot in Dallas during a peaceful protest over the fatal shootings of black men by police officers in Louisiana and Minnesota.

Dallas Police said two snipers shot 11 officers, killing three police officers and one DART (Dallas Area Rapid Transit) officer. One civilian was also shot and injured. Police say the snipers fired on officers from an elevated position.

During a press conference, Chief David Brown said they believed the shooters triangulated because some officers were shot in the back. He also said officers were combing downtown Dallas for what they believed was a bomb planted by the snipers.

Mayor Mike Rawlings also urged the city to "come together" in support of the fallen officers and their families.

Stay tuned to Fox News Channel for continuing updates.

WATCH: Witnesses Post Videos of Chaos Erupting at Dallas Protest

Dramatic video shows crowds running as gunfire broke out at the protest in downtown Dallas at 8:45 p.m.

The motivation of the shooter is not yet clear. The condition of the officers also is not clear.

Police are still hunting for the shooter.

10:35p - An eyewitness who was at the front of the protest gave an account of when shooting broke out. The man said that "it was almost like the gunshots were coming at us."

The man described the scene as "complete pandemonium." He also said that whoever was shooting had an "assault rifle," because of the rate of the sound of the gunshots.

10:48p - A man who participated in the march described the scene as peaceful before chaos broke out. Micheal Bautista had moved to the front of the group to take photos.

"Instead of getting photos, I ended up getting shot at," he said. He said that he hid behind his car until officers came to him. He then revealed to the reporter that he saw an officer get hit by a bullet.

11:06p - A witness described seeing an injured officer get carried off in a gurney.

11:30p - Veteran reporter Shaun Rabb shared the latest information from his police sources. Rabb said that between 5 and 6 officers were gravely wounded. "This is going to be a very horrible night before the sun rises," he said.

Stay tuned to Fox News Channel for the latest developments.