Dallas police identified Micah Xavier Johnson, a 25-year-old Army veteran, as the lone gunman in the shooting.

Detectives found bomb-making materials during a search of his home.

Johnson said he was upset about recent police shootings and wanted to kill white people, especially white officers, the police chief said.

Officers detonated a robot bomb to kill Johnson after attempting to negotiate with him.

President Barack Obama called the attack vicious, despicable, and calculated.