ROBERT SIEGEL, HOST:
It's been a wrenching week. Tuesday, a black man selling CDs outside a convenience store in Baton Rouge was killed by police. Wednesday, another black man in suburban St. Paul was killed after being pulled over for a broken taillight. Thursday, at the end of a march protesting those deaths, five police officers were killed and another seven wounded by gunfire in downtown Dallas. Now there's growing evidence that there was a single gunman acting alone. NPR national security correspondent David Welna is here to talk about what's known about last night's attack and what's known about that gunman. David, who was the suspect who was killed by police?
DAVID WELNA, BYLINE: Robert, his name is Micah Xavier Johnson. He was a 25-year-old African-American, and he lived with his mother in the East Dallas suburb of Mesquite. The only solid information we have about him is that he served in the Army Reserve for six years after high school, until April of last year. And during that time, he did a nine-month tour of duty in Afghanistan as a private first class, which he returned from two years ago, having earned seven medals and ribbons for his service. NBC News is reporting that he worked with mentally-challenged children and adults in Mesquite, helping with their transportation. And the Dallas Police say he had no criminal history.
SIEGEL: Are there any signs that he had been planning to carry out this attack?
WELNA: There are. Detectives who searched his home today say they found bomb-making materials, ballistic vests, rifles, ammunition and a personal journal of combat tactics. And in addition to that, NPR has obtained a manifesto from law enforcement officials, which appeared below a photo of Johnson in military uniform on social media. And they believe it was written by him. In it, the writer expresses disgust at seeing what he calls his brothers and sisters being killed by cops every day. And he says he had to take a stand to teach them a lesson. There's also an exhortation to others to carry out more violence, as well as a complaint that the Black Lives Matter movement has been damaged from within and needs to be taken back by force. Now, a caveat - this manifesto appears to have been posted after Johnson was killed, so it's not clear how he might have had it made public, whether it was through a delayed release or it was posted by another person.
SIEGEL: We first started to get some details about how Johnson was cornered this morning, during an emotional news conference in which Dallas Chief of Police David Brown spoke.
WELNA: Yes, and he described how this march in Dallas ended fairly peacefully, when suddenly shots were ringing out. And they seemed to all be aimed at the police. Now, this was just a short distance away from Dealey Plaza, where John F. Kennedy was assassinated. And the police eventually cornered a shooter in the second story of a parking garage. And Police Chief David Brown described the situation, saying that a standoff had begun.
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DAVID BROWN: And we tried to negotiate for several hours. Negotiations broke down. We had an exchange of gunfire with the suspect. We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was.
WELNA: Now, Chief Brown says that device killed the suspect. But before that happened, he said a hostage negotiator had done what he called an exceptional job getting that suspect to talk over a period of several hours.
SIEGEL: And it was - it was during that - that exchange between police and Johnson that some details were gained about - about a motive here.
WELNA: That's right. Chief Brown said the shooting was apparently in reprisal for the deaths this week of the two black men in Baton Rouge and the suburban St. Paul who were killed. This is what he had to say.
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BROWN: The suspect said he was upset about Black Lives Matter. He said he was upset about the recent police shootings. The suspect said he was upset at white people. The suspect stated he wanted to kill white people, especially white officers.
WELNA: The police chief also said that the suspect, who insisted that he was not affiliated with any other groups and said that he was acting alone.
SIEGEL: That's NPR's David Welna. David, thank you.
WELNA: You're welcome, Robert. Transcript provided by NPR, Copyright NPR.