Shots were fired shortly before 9 p.m.as hundreds of people demonstrated in downtown Dallas.
Inside his home in Mesquite, ATF and police investigators found bomb-making materials, rifles, ammunition, ballistic vets, as well as "a personal journal of combat tactics", DPD said Friday. Media accounts have reported three people in custody related to the shootings. The blast killed Johnson after he refused to surrender.
The incident happened during a peaceful protest over police brutality, after two black men were killed by police in separate incidents this week, fueling a heated national debate over the treatment of black people by law enforcement officers.
"It is a heartbreaking moment for the city of Dallas", Dallas Mayor Mike Rawlings said. It was believed he had become enraged after a spate of police shootings that resulted in the death of black suspects.
Early yesterday morning, dozens of officers filled the corridor of the emergency room at Baylor Medical Center, where wounded officers were taken.
The president defended police officers at another news conference Thursday about the shootings in Minnesota and Louisiana, saying they put their lives on the line.
But he added that many in law enforcement need to root out their racial bias.
Video footage from the Dallas scene showed protesters marching along a street, about half a mile from City Hall, when the shots erupted and the crowd scattered, seeking cover. The officer was married and the father of a 2-year-old daughter. Earlier, officials had said 11 officers had been shot.
Johnson, 25, is reportedly the shooter who was involved in the standoff with police overnight on Thursday.
The Justice Department is investigating Sterling's death. "No peace! No racist police!" Some larger police departments own unarmed drones or ground-based robots meant to detect or disarm explosives, Singer and Joh said.
The blowing up of the gunman suspected of murdering five police officers during a Black Lives Matter march is thought to be the first lethal use of a robot bomb in American policing.