Hillary Clinton has condemned the killing of three Louisiana police officers, and declared: "This madness has to stop."
The Democratic presidential candidate said police represent the "rule of law" and the shootings amount to taking aim "at all of us".
Mrs Clinton spoke at the NAACP national convention in Cincinnati a day after the fatal shootings in Baton Rouge.
She added that the recent killings of police officers in Dallas and now in Baton Rouge threaten the ability of the nation to make progress.
The former US Secretary of State said that anyone who kills a police officer or acts as an accomplice must be held accountable.
Recent violence has cost the lives of eight officers, including those in Baton Rouge, and two civilians, and it has sparked a national debate over race and policing.
Mrs Clinton has proposed a series of reforms to the criminal justice system, including developing national guidelines on the use of force by police, new investments in bias training, legislation to end racial profiling and funding for body cameras.
She has also pushed for cutting mandatory minimum sentences, particularly for drug offences, and providing better support to help the formerly incarcerated find jobs after prison.
"We have difficult, painful, essential work ahead of us to repair the bonds between our police and our communities and between and among each other," she said.
Mrs Clinton spoke as Republicans gathered for the first day of the party's national convention in Cleveland.
Mrs Clinton referenced presumptive Republican nominee Donald Trump's decision not to speak at the NAACP convention.
"My opponent may have a different view but there's nowhere I'd rather be than right here with all of you," she said.