Hillary Clinton said Monday she had met with the "courageous" family of Philando Castile and called for an end to the cycle of deaths involving police officers.
The presumptive Democrat nominee told the American Federation of Teachers convention in Minneapolis that the country had been "confronted with tragedy too many times recently."
"We cannot let this madness continue," she said. "This violence cannot stand."
She paid tribute to school kitchen supervisor Castile, who was fatally shot July 6 by police in nearby St. Paul during a traffic stop, saying she had met with his mother, two of his uncles and his sister.
"A lot of people are still in pain right here, including his courageous family, his coworkers and students at the St. Paul public schools, and our AFT brothers and sisters in the Twin Cities who knew him as a fellow educator who cared deeply about this community and its children," Clinton said. "His death, his loss, is ours as well."
She also praised the work of police officers in keeping communities safe, turning to the ambush killings of cops in Dallas, Texas and Baton Rouge, Louisiana, following Castile's death.
"Killing police officers is a crime against us all," she told the crowd. "There can be no justification, no looking the other way, and this must end. It can be true, both that we need law enforcement and that we need to improve law enforcement, to get back, to get back to the fundamental principle that everyone in every community benefits when there is respect for the law and everyone is respected by the law."
During her remarks, protesters marched to the stage chanting, "Hands up, don't shoot!"
Earlier Monday, Clinton shared a similar message to the NAACP conference in Ohio, calling for "all good people" to speak out against the escalation in violence.
At the AFT event, Clinton also stressed the importance of teachers' viewpoints.
"I'm with you," she said. "I personally have no time for these so-called education wars. It's time for those of us who believe in public education to sit at one table around it together and listen to you, the teachers … who actually are with our kids all day long."
Turning to politics, Clinton took a swipe at Donald Trump's VP pick Mike Pence, calling him a "Tea Party politician who has worked to undermine the rights of women, workers, LGBT Americans, and immigrants."
She said Pence has "cut millions from higher education while he was giving huge tax cuts to corporations," slashed funding for vulnerable students and "turned away" federal funding that could have expanded pre-school access to low-income children.
"He's one of the most hostile politicians in America when it comes to public education," Clinton told the crowd. "Neither Mike Pence nor Donald Trump should be anywhere near our children's education."