"This was a mobile shooter that has written manifestos on how to shoot and move. He did that. He did his damage. But we did our damage to him, as well," Dallas Mayor Mike Rawlings said after police carefully questioned and ruled out other potential suspects in the Thursday night rampage.

Investigators discovered bomb-making materials, rifles and a "personal journal of combat tactics" in the home of the black former Army reservist who struck during a demonstration against the shooting of two black men by white police officers in Minnesota and Louisiana.

Authorities identified the gunman as Micah Xavier Johnson, 25, a Dallas-area resident, a "loner" with no criminal history who "wanted to kill white people" and "especially white officers," police said.