Police in Dallas are still reeling from a massive sniper attack in which a lone gunman killed five officers and wounded several others on Thursday.
Dallas police have received an anonymous threat against officers across the city, and the department is taking extra safety precautions.
In Valdosta, Georgia, a police officer was shot Friday morning by a man who placed a 911 call to report a auto break-in at an apartment building, the Georgia Bureau of Investigation said. Only a minority of white people - and just 20 per cent of Republicans - support it. According to the Washington Post, which has been mapping the killings, of 509 people shot or killed by the USA police this year, 123 have been black, despite comprising only 12 per cent of the country's population. Reporters in the area were told to "get down".
After shooting at the Dallas officers, Johnson tried to take refuge in a parking garage and exchanged gunfire with police, authorities said.
Police did not immediately return a call for comment from Patch.
Reaction against the cold-blooded, entirely unjustifiable targeting of law enforcement officers should not drown out outrage against the seemingly endless string of killings of black people at the hands of police.
Among Dallas investigators' current goals: Figure out what Johnson had meant by "RB", lettering that Brown said he'd written on the wall in blood before his death.
Over the next two decades, attempts at reform continued, particularly after a series of officer-involved shootings in 2012 and 2013.
Two separate incidents seem to have refueled anger over police brutality, particularly toward black men, which has received increased attention since Michael Brown was killed in Ferguson, Missouri, in 2014.
There has been a marked improvement in the relationship between the Dallas police force and the black community, said Naomi Baxter, a member of Mothers Against Police Brutality, who attended the rally Thursday.
"We're convinced that this suspect had other plans and thought that what he was doing was righteous and believed that he was going to target law enforcement - make us pay for what he sees as law enforcement's efforts to punish people of color", Dallas Police Chief David Brown told CNN's "State of the Union".
Protesters have focused on the Minnesota governor's mansion in St. Paul since shortly after the shooting.
Brown said he became increasing concerned that "at a split second, he would charge us and take out many more before we would kill him". He fatally shot her, he said later, because he thought she was aiming the gun at him.
The police department in the Gulf Coast town of Waveland, Mississippi, is among those on alert after receiving what authorities there deem credible threats against officers.
"I would hope that police organizations are also respectful of the frustrations that people in these communities feel and not just dismiss these protests as political correctness or politics or attacks on police", he said. Glendening, who represented Johnson in the case, said the woman requested a military protective order against his client. He said people who aren't in law enforcement should be respectful of people who put their lives on the line to protect people.
The attack, which occurred in downtown Dallas just blocks from where John F. Kennedy was assassinated, left at least five police officers dead and six more injured.