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

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.

David O. Brown said a hostage negotiator was able to talk with the suspect for hours before police determined they had no choice but to move in to end the standoff at El Centro College.

Brown said the suspect was cornered for several hours, but negotiations broke down and there was an exchange of gunfire. 

He said officers determined that the only option was to use a "bomb robot," placing an explosive device on its extension and detonating it near the suspect. 

"Other options would have exposed our officers to grave danger," he said.

The suspect did not kill himself, said Brown, noting earlier inaccurate reports. Brown shared some of the comments made by the gunman before he was killed.

"He said he was upset about Black Lives Matter", said Brown, and was angry about recent police shootings and at white people.

The suspect stated he wanted to kill white people, especially white officers, said Brown. The suspect also warned about IEDs placed around the downtown area. 

The suspect stated he was not affiliated with any group and that he acted on his own.

Brown said the man seemed "lucid" during the talks.

A woman and two men are also in custody after being stopped a few miles away. Brown did not share any information on those individuals.

The investigation is continuing into whether there were more suspects involved in what appeared to be a coordinated assault.

Five police officers were killed in the sniper attack, with seven more injured, including some in critical condition. 

Two civilians were reportedly wounded as well, including a mother who was at the rally with her sons.

It was the deadliest attack on U.S. police officers since September 11, 2001.

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