Attorney General Loretta Lynch on Friday called the attack in Dallas an "unfathomable tragedy."
"This has been a week of profound grief and heartbreaking loss," Lynch said.
Her comments come after at least one attacker shot 12 police officers, five fatally, during a Thursday night protest over deadly police shootings of black men elsewhere. The attorney general said she was "heartbroken at this loss" and expressed her gratitude for the "difficult and dangerous work [officers] do every day to keep our streets safe and our nations secure."
In the wake of these deaths, Lynch said that "Americans across the county are feeling a sense of helplessness, of uncertainty and of fear."
"These feelings are understandable and they are justified. But the answer must not be violence. The answer is never violence. Rather, the answer must be action: calm, peaceful, collaborative and determined action," she said.
She listed a number of things that the United States could do in order to not let this become "a new normal in our country." She said more needs to be done "to build trust between communities and law enforcement" and "to guarantee every person in this country equal justice under the law."
Lynch also addressed activists "who seek to improve our country through peaceful protest and protected speech."
"I want you to know that your voice is important. Do not be discouraged by those who use your lawful actions as cover for their heinous violence. We will continue to safeguard your constitutional rights and to work with you in the difficult mission of building a better nation and a brighter future," she said.
The attorney general asked Americans to avoid giving in to the "easy impulses of bitterness and rancor."
"Above all, we must remind ourselves that we are all Americans — and that, as Americans, we share not just a common land, but a common life," Lynch said.