At a campaign rally in Orlando, Fla., Hillary Clinton spoke about the shootings here and in Tulsa.

“There is still much we don’t know about what happened in both incidents, but we do know that we have two more names to add to a list of African-Americans killed by police officers in these encounters,’’ she said.

“It’s unbearable, and it needs to become intolerable. We also saw the targeting of police officers in Philadelphia last week. And last night in Charlotte, 12 officers were injured in demonstrations following Keith Scott’s death. Every day police officers are serving with courage, honor and skill.”

Her Republican rival, Donald J. Trump, reacted on Twitter. “Hopefully the violence & unrest in Charlotte will come to an immediate end,” he wrote. “To those injured, get well soon. We need unity & leadership.”

Unity, thus far, has been in short supply. On Friday, Mr. Trump earned the endorsement of the Fraternal Order of Police. But polls show that his support among African-Americans is negligible, even though he has singled them out in promising to solve the ills of poverty and violence that he has characterized as plaguing black neighborhoods.

On Wednesday, Mr. Jackson, the man who came here to mourn, was not thinking about the current presidential candidates.

The police, he said, “are out here killing people, and they don’t even know their backgrounds,” he said. “They could be killing the next president.”