Police investigators are combing through hundreds of hours of video evidence to know what happened.
Dallas Police Chief David Brown on Monday defended the use of a bomb-carrying robot to kill the gunman who went on a shooting rampage last week targeting police and killing five officers.
Brown also updated the number of officers wounded in Thursday's sniper attack -- which took place during a peaceful protest over the fatal police shootings of two black men elsewhere in the United States -- from seven to nine.
Two civilians were also wounded in the ambush.
"This wasn't an ethical dilemma for me. I'd do it again," Brown said when asked about the use of a bomb robot to end the hours-long showdown with the shooter, identified as black Afghanistan war veteran Micah Johnson.
The 25-year-old Johnson told negotiators he was angry over police treatment of black men and was specifically targeting white cops. He was killed in the explosion.
"I would use any tool necessary to save our officer's lives. I'm not ashamed to say it," Brown said.
The $150,000 robot police employed is normally used as a bomb disposal tool. It is a remote-controlled machine with a camera to aid the operator and 60 pounds of weight capacity.
In what is believed to be the first instance of its kind on US soil, police "improvised" the modified use of the robot to deliver a one pound brick of the plastic explosive C-4.
The process took about 15 to 20 minutes, Brown said, with his only guidance to officers being: "Don't bring the building down."
The chief told reporters that Johnson, who used a high-powered rifle, may have been planning a major bomb attack, with a "large stockpile" of bomb-making materials found at his home.
"He knew what he was doing. This wasn't some novice," Brown said. "We don't think he learned that in the military. We don't have any evidence of that."
Police investigators are combing through hundreds of hours of video evidence -- from officer body cameras, dash cams and nearby businesses -- to try to piece together what happened.
"Detectives are reviewing over 300 statements to determine which witnesses and officers need to be brought back for further interviews," Brown added.
As that work continued, the city tried to come to terms with the shooting.
Civilians and police gathered for a moment of silence at a makeshift memorial in front of the Dallas Police Department headquarters. Officers stood in a line, as others assembled in a circle around a police car covered with balloons and flowers.
President Barack Obama and former president George W. Bush plan to speak at an interfaith memorial in Dallas on Tuesday for the five killed officers.
Dallas police announced plans for the first three of the officers' funerals, which will take place on Wednesday and Thursday.
Senior Corporal Lorne Ahrens of the Dallas Police Department and Brent Thompson of the Dallas Area Rapid Transit police will be laid to rest on Wednesday.
Funeral services for Sergeant Michael Smith of the Dallas Police Department are planned for Thursday.
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