UPDATE 5:21 p.m. ET: In a statement released Friday afternoon, the Dallas Police Department revealed that a search of the suspect's home revealed "bomb-making materials, ballistic vests, rifles, ammunition, and a personal journal of combat tactics." Another man, identified as 25-year-old Brandon Waller, was arrested on "unrelated weapons charges" following the search.

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A gunman responsible for fatally shooting five police officers and wounding nine other people, two of them civilians, at a Black Lives Matter protest march on Thursday night has been identified as Micah Xavier Johnson.

Police used a robotic bomb to kill Johnson at around 2:30 a.m. Friday morning when "negotiations broke down" with the suspect and they exchanged gunfire with him. Police previously said they took four suspects into custody but are now reporting Johnson may have acted alone. Dallas police chief David Brown said in a press conference following the tragedy that their search for those responsible would be extensive. 

"I'm not going to be satisfied until we've turned over every stone," he said. "We've got some level that this one suspect did do some of the shooting. But we're not satisfied that we've exhausted every lead. So if there's someone out there who's associated with this, we will find you, we will prosecute you, and we will bring you to justice."

The 25-year-old shooter served as a carpentry and masonry specialist in the Army reserve, officials said, and was deployed to Afghanistan in November 2013. He had recently been residing in the Dallas area with his mother, a neighbor told CNN, and mostly "[kept] to himself." Brown said during negotiations that Jones claimed he acted alone, fueled by a hatred of white people and police officers. 

"The suspect said he was upset about Black Lives Matter," he said. "He said he was upset about the recent police shootings. The suspect said he was upset with white people. The suspect said he wanted to kill white people, especially white officers. The suspect stated he was not affiliated with any groups and he stated that he did this alone." 

According to officials at the Department of Homeland Security, Johnson "appears to have been" the only gunman in Dallas. Furthermore, there were no links to any international terrorist groups, BuzzFeed reportsThe Daily Beast reported he identified as a "black nationalist" on his Facebook page and had a photo of a black liberation flag as his cover photo. The suspect had taken self defense and personal protection courses at Academy of Combat Warrior Arts in Richardson and Fort Worth. 

The Los Angeles Times reported that a deleted post on a Facebook page of the shooter's sister read, "I keep saying it’s not true." Another post said, "The news will say what they think, but those that knew him know this wasn’t like him. This is the biggest loss we’ve had."