"This madness has to stop," she said at the civil rights organization’s annual conference in Cincinnati.
A former U.S. Marine shot the officers Sunday in Baton Rouge.
"Watching the news from Baton Rouge yesterday, my heart broke. Not just for those officers and their grieving families, but for all of us," Clinton said. "We have difficult, painful, essential work ahead of us to repair the bonds between our police and communities and between and among each other. We need one another to do this work and we need leaders like the NAACP.
The incident followed the killing of five law enforcement officers in Dallas last week, and the recent police-involved shootings of Alton Sterling in Baton Rouge, Louisiana, and Philando Castile in Falcon Heights, Minnesota, which caused widespread protests across the country.
Clinton lamented the tragedies during her remarks to the NAACP today.
"Many African-Americans fear the police. I can hear you. Some of you in this room," she said at the NAACP annual conference. "And today, there are people all across America sick over what happened in Baton Rouge and in Dallas but also fearful that the murders of police officers means that vital questions about police-community relations will go unanswered."
The presumptive Democratic nominee vowed, if elected president, to reform the U.S. criminal justice system and also make sure that those who murder law enforcement officers are held accountable.
"As president, l will bring the full weight of the law to bear and making sure those who kill police officers are brought to justice," Clinton said. "And let's admit it, there is clear evidence that African-Americans are disproportionately killed in police incidents compared to any other group. And African-American men are far more likely to be stopped and searched by police, charged with crimes and sentenced to longer prison terms than white men convicted of the same offenses. These facts tell us something is profoundly wrong. We can't ignore that, we can't wish it away.
She continued, "We have to make it right. That means end-to-end reform in our criminal justice system, not half measures, but a full commitment with real follow-through."
In response to Sunday's shooting in Baton Rouge, presumptive Republican nominee Donald Trump tweeted his condolences.
“We grieve for the officers killed in Baton Rouge today. How many law enforcement and people have to die because of a lack of leadership in our country? We demand law and order,” he wrote.
Clinton’s appearance at the NAACP falls on the first day of the Republican National Convention in Cleveland. Trump was also invited to speak to the group, but declined the invitation.
"We all know about that other convention happening up in Cleveland today," Clinton said. "My opponent in this race might have a different view, but there's nowhere I'd rather be than right here with all of you."
Unlike past presidential elections where candidates take the week off the campaign trail during the opposing candidate’s convention, Clinton will be on the road.
She has campaign events planned this week in Ohio, Minnesota and Nevada, and is expected to announce her running mate sometime later this week.